TunnelTalk Special Edition: India Focus and Case Studies

Direct by Design

SPECIAL EDITION FOCUS: INDIA CASE STUDIES

https://tai.org.in/about-tai/

PROMOTING ACCELERATED DEVELOPMENT AND USE OF TUNNELS AND UNDERGROUND SPACE

TAI

PROMOTING AMONGACCELERATED TAI ASSOCIATED PARTNERS DEVELOPMENT AND USE OF TUNNELS AND UNDERGROUND SPACE

TUNNELLING ASSOCIATION OF INDIA

TAIym 35

[Affiliated to International Tunnelling and Underground Space Association (ITA)]

TAI

TUNNELLING ASSOCIATION OF INDIA

TAIy 35

[Affiliated to International Tunnelling and Underground Space Associa

ym 5

SPECIAL EDITION FOCUS: INDIA CASE STUDIES FROM THE EDITOR’S DESK

India on fast track to the future

F

rom being reported as a reluctant powerhouse a decade ago, India is currently experiencing a national boom in economic growth and international recognition (p48). Spearheaded by the Government of Prime Minister Narendra Modi, in Government since May 2014 and expected to be re-elected for another term in 2024, investment in national infrastructure is the necessary foundation of these aspiration. The need is great and the commitment is there, including for major underground works. Public and private funding of hydro power schemes, national road and rail connectivity, rolling programmes of metro expansion, regional rail integration, and urban water and wastewater management investments all point to an era of fast-track nation building for India.

Following many visits to India and after reporting on major underground projects over the decades, the speed of rollout, and the commitment to achieve the best in underground construction, has been impressive with many setbacks providing the resolve and determination to succeed. The reporting started in 1998 with a visit to the Konkan railway project where so many civil engineers currently in senior positions with clients, consulting and contracting organisations in India today, began their careers and were being introduced to the possibilities, principally under the guidance and leadership of civil engineer E. Sreedharan of Kerala State as head of the Konkan Railway Corporation and charged with bringing the 760km long railway along the west coast of India into reality (p4). Adopting a firm but fair style of leadership, and insisting on the import of modern construction equipment and knowhow, particularly for the underground elements of the line, earned for Sreedharan a high reputation. After completion of the Konkan railway, Sreedharan became Managing Director of the Delhi Metro Corporation at the beginning of the Delhi Metro development and the start of its first underground alignments (p9). This Building the Konkan Railway Metro and rapid transit systems Delhi Metro Bangalore Metro Mumbai Metro Kolkata Metro Chennai Metro

ation (ITA)] Direct by Design

4 8 9 21 33 39 39

began the rollout of metro development across the capital city as well as across the nation, earning Sreedharan the moniker of Metro Man and seeing the Delhi Metro Corporation model adopted for metro development for many of India’s mega cities.

In the 20 years since the end of the Konkan railway project and the start of the first underground lines of the Delhi Metro, the underground construction industry of India, comprising both national and international engineers, contractors, machine manufacturers and material suppliers, has gone from strength to strength with construction of the first underground metro line for Mumbai, Line 3, demonstrating world-class underground achievements and cutting-edge technological advancements. Among the many, one of these is the first use in the world of an underground metro station finished with a drained sprayed waterproofing membrane system and a final inner lining of steel fibre reinforced shotcrete.

The development of the method is a finalist in the 2023 series of the ITA Awards in the category of Beyond Engineering.

With the spirit of collaboration and can-do, the underground construction industry of India has heeded the call of the national Government, and is leading the charge for developing road, rail and hydro schemes, including in the foothills of the Himalayas where excavation efforts of the past have been defeated, and taken up the urgent demands for improving the traffic, air quality, and water management needs in the towns, villages and megacities of the country. The world watches as India makes its charge. n

Shani Wallis, TunnelTalk

Lucknow Metro Pune Metro Agra Metro Regional commuter rail networks Nation building in India India hosts WTC and ITA GA 2008 Rohtang pushed NATM to the limits

41 42 43 44 46 48 50

Copyright© TunnelTalk 2023. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic or otherwise, without the prior permission of the copyright owner. All views expressed in this journal are those of the respective contributors and are not necessarily the opinions of the publisher, neither do the publishers endorse any of the claims made in the articles or the advertisements.

www.TunnelTalk.com ContactUs@TunnelTalk.com

CASE STUDY: Many would say that the modern era of underground construction in India began with the Konkan Railway. Under the leadership of civil engineer E Sreedharan as Managing Director of the Konkan Railway Corporation, a new method of public infrastructure funding was adopted, elements of outstanding engineering design were completed and the latest in underground construction methods, equipment and materials were imported. From the success and the lessons learned on the Konkan Railway, the underground industry of India of today has grown.

Building the Konkan Railway SEPTEMBER 1998

I

n 1990, managers of the Konkan Railway Corporation of India were looking for office space in Mumbai. Eight years later, they were running a 760km long passenger and freight railway, the first project in this government-based bureaucracy to be built on a build-operate-transfer BOT basis. A main line railway between Mumbai and Mangalore has long been considered the missing link in India’s otherwise extensive rail network. Previously, rail traffic from Mumbai had to cross the sub-continent to Madras, or Chennai as it is today, then back again to Mangalore, a distance of 2,050km taking 41 hours, as opposed to 914km taking 15 hours with the new railway (Fig 1).

Initially, the proposed alignment between the existing railhead at Roha, about 140km south of Mumbai, and

Fig 1. Some 83.6km of the 760km long Konkan railway between Roha (south of Mumbai) and Mangalore along the west coast of India runs in 92 tunnels and cuts the current cross country route from 41 to 15 hours

Mangalore was 837km long with 37km in tunnel. An upgrade to accommodate train speeds of 160km/hr saw the gradient straightened to minimum 1,250m radius curves and flattened to a maximum 1:150 gradient to give a shorter 760km alignment, with 83.6km in 92 tunnels.

Electrification of the line and doubling of the single track are envisaged.

Some 74km of the 83.6km of tunnelling is hard rock excavation through basalt at the north end and granite in the south. The basalt and granite have RQD values of 90-95 and very little overbreak or immediate support was anticipated in these long lengths of tunnel. The remaining 10km was identified as soft ground tunnelling through nine short tunnels in the middle section of the line, in and either side of Goa. The single­track tunnel profiles are a standardised straight-sided inverted

Project finances

A

s a BOT finance and construct project, the Ministry of Railways, with the four beneficiary State Governments of Maharashtra, Goa, Karnataka and Kerala, set up the Konkan Railway Corporation to operate as a public sector selfmanaged organisation under the Ministry of Railways and provided it with an authorised starting capital of 6 billion INR. Further funding was raised through tax-free Government bonds yielding a guaranteed 10.5%.

First estimate for the five-year construction phase of the 760km long, single-track railway in 1991 prices was 14 billion INR. Since then, the budget at the end of the construction phase in early 1998 (including escalation, contingencies, delays, and extras) has risen to 24 billion INR. Add the 6.6 billion INR cost of finance during construction, and the total cost at the end of construction is 30.6 billion INR or US$769 million at May 1998 prices of 39.8 Indian Rupees to US$1.

“What we must do now is make sure the railway pays for itself,” said Rajaram, current KRC Director and previous Financial Director of the Corporation, and also a civil engineer previously with the Ministry of Railways. Fortunately, a large portion of the initial revenue potential or market is already established because traffic making the long cross-country journey between Mumbai and Mangalore will inevitably transfer to the shorter direct Konkan Railway route. Secondly, passenger and freight rates on all Indian railways are fixed by law through the Ministry of Railways. There can be no price wars or fierce undercutting competition.

“With a conservative empty haulage rate of 50%, we can meet all our loan and bond obligations within the specified ten years,” said Rajaram, “providing our operating and maintenance costs are kept to a maximum 32% of total income.”

4

From left: Fig 2. Single-track profiles and support lining designs; Completed section of one of the longest unlined rock tunnels in which the necessary ventilation fans for diesel train traffic will be fixed to the tunnel crown

U-sections of approximately 4.6m wide x 5.8m high and about 30m2, with various support systems (Fig 2).

negotiated favourable power supply agreements for the new machines.

Because part of the BOT commitment was to have the new line built and in operation in five years, tunnelling was on the critical path. Nine of the rock tunnels are longer than 2km each and the 6.5km tunnel was the longest transportation tunnel in India at the time.

Among the several firsts introduced to achieve its goal, Konkan Railway Corporation (KRC) specified the use of modern drilling jumbos and muck loading equipment on the longer rock tunnels - considered the project’s most critical elements - and bought nine Atlas Copco H 135/352 electro-hydraulic two-boom + basket Boomers with a Hagglund loader/mucking system.

Despite this, initial response to the imported equipment was at best unenthusiastic. Contracts had to be terminated due to lack of progress and, in one case, the corporation itself had to take over to demonstrate the potential of the mechanised methods and how to use them to achieve optimum productivity. Eventually, 19km of the 74km of rock tunnelling was completed with the Boomers and Hag loaders.

It was however the shorter 10km of soft ground tunnelling that proved the most troublesome. In November 1997, it was the last 35m of the Pernem tunnel in Goa, begun from both portals in March 1992, that was delaying the start of through-train services on the line.

Construction of the 92 tunnels was packaged into individual contracts for the 17 longest tunnels and packages of two to eight tunnels each for the remaining 75. Bids were invited from shortlists of contractors selected from a limited tender process in which previous experience was among the major selection criteria. Few Indian contractors in 1990 however had experience of modern tunnelling technology. While traditional methods were used on more than 50km of the rock tunnels, it was against great resistance that KRC insisted that modern machinery be used on the longer rock tunnels.

To overcome this resistance, and in addition to its direct purchase of the Atlas Copco jumbos and the Hag loaders, the corporation provided contractors with 10% mobilization and 10% plant and machinery advances as commercial incentives; it procured and distributed all the explosives at fixed costs; and it

Rock tunnelling generally progressed steadily. Best cycle times of 4hr 25min for a 3.5m pull were achieved using the imported equipment, with peaks of 204m/month working 24hr/day, 7 days/week. The 55km of hard rock held jack hammers tunnelling completed using hand­ reached peaks of 106m/month. Explosive consumption averaged 1.5kg/m3.

Problems on the hard rock tunnels centred on the unexpected encountering of softer, more unstable conditions. In the north heading of the 3.7km long Sawarde Tunnel, columnar basalt, undetected by the site investigation, caused frequent rockslides. Only 400m was accomplished from the north portal with the remaining 3,260m excavated from the south. On the longest tunnel, full face advance using an Atlas Copco jumbo was delayed for two years by a 400m length of unstable ground, requiring cautious topheading and benching work and advance from two of the three 6.1m diameter ventilation shafts to finish excavation in 44 months.

On the 850m long Mudgere Tunnel, work had advanced from the south portal alone for some 675m without incident. The contractor was confident of breaking through without needing to open a north portal heading until a routine blast initiated an inundation of mud and soft ground. A sudden reduction of the rock cover above the crown at this point caused a collapse and 5

a sinkhole of 30m diameter and 12m slump appeared on the surface.

Fig 3. Multi-drift technique used to excavate the top heading in the soft ground tunnels

Because it was impossible to continue from the south portal, slow top-heading and benching started from the north with controlled blasting to avoid further failure of the thin 2-4m rock cover.

The fall occurred in August 1994 and the tunnel was eventually completed in June 1996. Grout injection from the surface with careful steel support facilitated advance and immediate casting of the final 500mm thick in-situ concrete lining recovered the collapsed zone.

Troublesome Pernem Tunnel

E

xcavation of the last tunnel to finish, the 1.5km long Pernem Tunnel, began in March 1992. Slow hand mining through soft material had progressed about 500m from the south portal and drill+blast though strong schist had progressed to about 970m from the north portal when by November 1997 only 34-40m separated the two fronts (Fig 4). But working towards breakthrough was proving endless. Topheading and benching was progressing from the south portal at about 1.5m in every 24hr while tunnellers from the north portal were struggling to recover from a series of five or six successive collapses.

The first sign of trouble in the north portal heading was a small roof collapse about 9m behind the face. The new face at the time was being charged and 55 drill holes were already loaded. Although a blast could well cause further trouble, there was no alternative. “We could not empty the changed holes,” said Engineer Natrajan, KRC Deputy Chief Engineer on the Pernem Tunnel north portal. “The 55 holes were blasted and just as mucking out was nearly finished, a series of large boulders fell from the face followed by flows of dry soil. Thankfully it was the dry season, but nevertheless, an estimated 800m3 of material collapsed into the hearing.”

ISMB beams of the wall plates (two each side (Fig 3)) were inserted and encased in concrete. Next a narrow niche around the profile was excavated into which the two halves of the 200 x 100 crown arch beams were erected and the lagging and backfill inserted. The core was then excavated by shovelling sticky clay clods into trolleys which were pushed by hand to the edge of the top heading and dumped into the bed of the dump trucks.

Meanwhile, bench excavation progressed in an equally cautious and painstaking manner. Behind that, the tunnel invert was being cast, as were the walls and the crown arch of the final in-situ concrete lining. Assistant Civil Engineer Joseph George said: “We have tried everything in this soft ground – shields, roadheaders, forepoling, which in wet conditions seemed to aggravate the problems, and even trials of shotcreting – but nothing has been successful. What we are doing with hand mining is very slow, but it is the best we can do. We are making progress and eventually we will get through.”

The topheadings of the Pernem Tunnel did breakthrough – in December 1997. Bench excavation finished in early January 1998. The lining was completed at the end of January 1998 and this last section of the Konkan railway line opened on 26 January 1998.

Once things were stabilised, work began to recover the situation. At first, any work at the face caused the loose dry material to run. “It was our Chairman Mr Sreedharan who said we Fig 4. The geology of the Pernem Tunnel as predicted by the 14 cores should wet the soil to get it to stabilise,” said recovered from the 100m overburden Natrajan. “We did so and it did.”

When TunnelTalk was on site, another 12m was yet to be mucked out before the pre-collapse heading could be reached.

Meanwhile, groundwater had percolated into the working faced turning the heading into a hot, humid den of wet, sticky mud.

Each painstaking cycle in the topheading began with hand-excavation of two 0.5m deep holes into which the four 200 x 100 6

Soft ground woes

It was the lack of experience with soft ground tunnelling that made the 9.6km of soft ground tunnels the really critical elements on the entire project. The geology of the middle Goa region is of volcanic origin and has a hard but porous lateritic surface crust with soft lithomargic clays and silts beneath. Problems arose largely in the monsoon season when torrential rain seeped through the porous laterite crust and turned the clay underneath to mud. Squeezing conditions, highly disturbed zones and inflows of saturated mud were common events. Sometimes, cavities were created above and in front of the face, which could extend to the laterite crust and often causing sinkholes on the surface.

According to Engineer Limaye, Chief Tunnelling Engineer with KRC, several TunnelTalk meets Dr Sreedharan in November 2008 in DMRC headquarters methods were tried to cope with these conspicuous by its absence. “At one stage we (KRC) did conditions. Perforated pipes of 150mm diameter and up buy several shotcreting systems, but they were difficult to 12m long were installed on 1:14 inclines and 1m centres to use effectively,” said Limaye. “We bought wet mix around the profile to try to drain the groundwater. Top systems which really needed efficient on-site batching headings were divided into multiple drifts using 200 x plants and transportation systems as well as high125 ISMS steel beams and wooden lagging to support volume applications to be effective. We had not set up the initial central excavation ahead of two sidewall drifts. our tunnelling to use shotcrete, we didn’t think it would Grout injection ahead of the face and from the surface be necessary. Each time we decided to invest in more was carried out and spiling with 30mm diameter pipe suitable dry mix systems, we were either back into better up to 6m long and on 200mm centres was used to form tunnelling conditions or thought we had only such a little pipe umbrella pre-support (Fig 3). left to do that we could get through without them.”

In squeezing zones, struts had to be inserted across “There is no doubt that NATM with lattice girders and the top heading invert between arch footings to shotcrete could have brought about improvement in increase stability. On some occasions, these had to be the speed of construction of soft soil tunnels...,” added embedded in concrete to be effective, the concrete and Limaye. “Perhaps obtaining expertise from abroad in strut being withdrawn with bench excavation. At other terms of personnel, equipment and contracting agencies locations where the clay strata had been disturbed, to implement NATM in soft soil tunnels would have been the vertical ISMB250 steel supports in the bench were a better course of action.” being displaced before the closing invert strut could be installed.

Completion of the Konkan railway tunnels has been hard won, with lives unfortunately lost in the endeavour.

All these efforts met with only limited success. Eventually, But the corporation and certain contractors now have top heading excavation in soft ground tunnels had to a wealth of newfound experience. Mr Sreedharan, stop for the three months of the monsoon season and for Chairman and Managing Director of KRC, has since two or three months after. Except in very dry conditions, accepted the post of Managing Director of the proposed working in these soft ground tunnels was a battle of slow Delhi Metro project, and the corporation has been manual labour against slush and mud with the increased consulted by other Government agencies. risk of collapse in the time taken between excavation and in­stallation of primary support. Various mechanical methods were tried to speed up excavation, including When TunnelTalk met Mr Sreedharan again in Delhi on clay diggers, electric conveyor belt systems for loading the Delhi Metro project in 2010, he was disappointed muck tippers and trolleys, and JCB excavators working with the outcome of the Konkan railway project with the top heading faces. A Westfalia and an Alpine Miner one of the greatest laments being that the Government AM50 roadheader were also deployed but these of India failed to positively support the use of the machines brought little satisfaction.

BOT railway by the Government owned India Railway Authority. There were to be positive Government supported advantages of using the new Government“In the course of struggling with soft soil tunnelling, we owned private-Corporation’s railway but these did not had many international experts coming to advise us, materialise and operators continued to use the longer, but all have been theoretical, advising on mathematical less expensive cross country route from Mumbai to models and computer programs. Few had solid practical Managlore. Today the railway operator continues to advice, which is what we needed,” said Engineer struggle to keep earnings ahead of operating expenses Natrajan. “We had to resort to traditional manual labour and other corporate costs. The railway however is an methods to make any headway at all.” acknowledged major engineering achievement and a valuable addition to the extensive network of freight and During the visit to the soft ground tunnels, the use passenger rail services throughout the country. n of shotcrete as an immediate support system was 7

Metro and rapid transit systems

S

taying up to date with plans and approvals for new metro and rapid transit systems in India is an everchanging task. The data is in a constant state of update and revision.

Development of metro systems in India is under the central Ministry of Urban Development and during his tenure as Urban Development Minister, from 2011 to 2014, Kamal Nath was instrumental in changing legislative regulations to ease barriers on import of specialist equipment and expanding access to different project funding vehicles including private public partnership models for expediting projects into construction in Mumbai and Hyderabad. Other cities have developed their systems under full funding by the Central and State Governments but regardless the funding model, it was Nath who said in 2011: “If State Governments come with the proposal for metro rail in cities of 2 million-plus population, the Ministry is ready to consider requests for supporting the plans with national funding.”

A population census at the time, identified 19 cities with more than 2 million residents and by 2019, nine metro projects were under different stages of implementation – Kolkata, Delhi, Bangalore, Mumbai, Chennai, Hyderabad, Lucknow, Pune and Ahmedabad.

Kolkata was the first city in the country to A growing number of cities in India with a population of more than a develop a metro system, opening its first million, are developing mass rapid transit and commuter rail link systems operating system in 1984. The initial operating rapid transit systems, several of the with sections of system included a hard-won underground section of bored underground alignment - Agra, Jaipur, Nagpur, Patna, and cut-and-cover construction supported by tunnelling Surat, Bhopal, Meerut, Indore, Kanpur, Kochi, Navi expertise from Hungary. At present the city is constructing Mumbai, the Noida and Gurgaon satellite cities of Delhi. a 14.67km east-west extension with a bored section under Another 10 cities and more are considering or well the Hooghly River to connect Howrah Maidan station on into the planning phases of public metro and metrolite the west bank to Central Station on the east. systems and continuing to roll out existing metro systems, several with sections of underground alignment Development of the metro system for Delhi was next in including Bangalore, which is currently constructing it the early 2000s. Initially, procurement was based on the third line (p21) and Mumbai, which adopted underground Kolkata model, but the construction authority, the Delhi alignment for the entire length of its Metro Line 3 (p33).

Metro Rail Corporation (DMRC), soon found its own way forward. Under initial Managing Director Dr Sreedharan, Added to these metro systems and plans, is development DMRC embarked on an ambitious metro development programme and from the first Video by India’s National Capital Region Transport Corporation section of underground alignment in the early (NCRTC) explaining the development of metro systems in India and the 2000s (p8), the city now has an operating commuter rail links being developed for the Delhi capital city region network of more than 213km, with long lengths underground. More than a third, or 50km, of the 159km Phase III programme and more than 40km of the 100km Phase IV programme is aligned underground.

In recent years, Central Government support of national infrastructure has continued under current Minister of Urban Development Venkaiah Naidu, who took over from Minister Nath in May 2014 as part of Prime Minister Modi’s administration, and today another 13 cities have started construction of metro 8

of regional commuter rail systems providing efficient travel for workers from satellite residential suburb cities to offices in main city centres and hubs. One of these is the regional rapid transit rail link between in Delhi to the satellite city of Meerut with underground sections at the Delhi and Meerut city approaches. TunnelTalk visited the Meerut end of this first line of eight corridors in the Regional Rapid Transit System (RRTS) network earlier in 2023 to see three 7.56mm diameter Terratec TBMs excavating the twin tube underground alignment between open cut stations (p44).

With the metro and regional rail projects, together with nationwide road, rail, water magazine and hydro schemes, in construction and in development, the need for underground construction equipment and materials,

design, construction and management expertise in India has never been greater. With this in mind the Tunnelling Association of India (TAI) is fostering the sharing of knowledge and ensuring the introduction of best practices among its membership both within India and supporting the collaboration of international companies working in India and through its Member Nation status of the ITA, International Tunnelling and Underground Space Association (p2). As well as supporting corporate and individual membership activities, the TAI has hosted and endorsed several international conference events in India, including the World Tunnel Congress in Agra in 2008, several exhibition trade shows (p46) and is hosting the Tunnelling Asia Conference and the 9th edition of the ITA Awards in Mumbai in November 2023. n

Delhi Metro emerging D

elhi made a determined start on its ambitious plans to bring modern mass transit services to its 13.8 million residents in the late 1990s with construction of the first three lines (62.5km) of an ultimate 198km network.

Sanctioned in 1995 and with a value of US$997.8 million (1996 estimate excluding inflation) the investment was programmed over a 10-year period to have all three lines operating by September 2005.

Of the initial three lines, all of Line 2 at 11km long is underground and has 10 underground stations. Line 1 is either atgrade or elevated, as is most of Line 3 after a 2km long underground section in the central Connaught Place areas.

Construction started on Line 1 in late 1998 with services on the first 8.5km section scheduled to start in December 2002.

Work on Line 2 also started, following the award of two contracts in early 2001 (Table 1), and Line 3 was in design for an anticipated invitation to tender in April/ May 2002.

Despite the fact that the project is running behind schedule, the Delhi Metro Rail Corporation (DMRC) still intends to pursue its planned 10-year schedule. “There was

Shani Wallis, TunnelTalk

MARCH 2002

Table 1. Design-build procurement of Line 2 and system-wide installations under Japanese project funding Contract Package Contractor Line 2 - Package MC1A Vishwa Vidyalaya to ISBT Design-build civil works plus ventilation and air conditioning facilities

Kumagai Gumi (Japan) - Leader Skanska (Sweden) Hindustan Construction (India) Itochu Corporation (Japan) Group Design consultant Manusell (Australia) Dyckerhoff & Widmann (Germany) - Leader

Line 2 - Package MC1B

Shimizu Corporation (Japan)

ISBT to Central Secretariat

Larsen & Toubro (India)

Design-build civil works plus ventilation

Samsung (Korea)

and air conditioning facilities

IRCON International (India)

System-wide - rolling stock

Design consultant Mott MacDonald (UK) Mitsubishi Corporation (Japan)

Design, manufacture, supply and

KOROS (Korea)

commission

Mitsubishi Electric Corporation (Japan) Alstom Transport Ltd (India and France)

System-wide - signalling/train control and communications

Alcatel Portugal

System-wide - traction, power distribution

Sumitomo Corporation (Japan) IRCON International (India)

and SCADA System-wide - automatic fare collection System-wide - supply, installation, test and

Cobra and ELIOP (Spain) Alcatel CGA Transport (France) ABB Ltd (India)

commission power supply System-wide - supply, installation, test and

Best & Crompton Engineering (India) IRCON International (India)

commission ballastless track

MVM Rail (Australia)

From left: Phase I and Phase II network; Chawri Bazar area where bored tunnels and a NATM station are needed

9

Fig 1. Geological section of the 11km long Line 2 with difficult mixed ground conditions anticipated at Chawri Bazar Station

a delay of two and a half years in setting up the corporation,” explains Managing Director, Dr Sreedharan. “Then there were delays in awarding the initial contracts and the two Line 2 design-build contracts, giving a contractual end date of March 2006 for the larger 60-month MC1B contract. We hope to make up these delays and have commitments from the two design-build contractors to work towards the original 2005 completion date.”

“This is a tough challenge for us,” said Rupert Sternath, Project Leader for the MC1B consortium International Metro Civil Constructors (IMCC), “but having agreed to it, we have established our schedule to meet the goal.”

Serving the most overcrowded areas of central Delhi, Line 2 was forced underground. The specified methods of construction then divided the Line into two large contracts. The 4.5km MC1A northern section with four stations is designed as open cut, including the running tunnels. The 6.5km MCIB southern section requires bored tunnelling with a 1.4km section of open cut possible from Patel Chowk to Central Secretariat Stations. Of the six stations five are open cut with the one beneath the Chawri Bazar to be mined.

Design-build procurement

International design-build procurement for Line 2 was part of the project’s funding arrangements. Some 56% of the Phase 1 project is financed through a soft loan agreement with the Japan Bank of International Cooperation (JBIC) with 30% funded through equal equity contributions from DMRC’s two Government stakeholders; the central government of India and the State Government of Delhi. The remaining 6% is raised through property development opportunities along the lines. The JBIC funding is not a tied loan explained Sreedharan, but “required that the project be reviewed and supervised by an international consultant, that the Line 2 contracts be open to international bid, and that construction be procured under design-build contracts. The World Bank and Asia Development Bank were also interested in the project but JBIC offered the more favourable terms and made funds available within the shortest lead time.”

To comply with the first requirement, the consulting JV of Pacific Consultants International of Japan (leader), Parsons Brinckerhoff International (USA), Japan Railway Technical Services, and Tonichi Engineering Consultants (Japan), and Rail India Technical and Economic Services 10

(RITES) was appointed General Consultant in September 1998. Prior to that, RITES, the engineering company owned by India’s National Rail Corporation, had managed development of the metro.

“As General Consultants we reviewed all existing design and contract documents and we are managing design for all of Line 2 and for two thirds of Line 1,” explained Tony Burchell, Project Director for the JV. “30% of the design was completed for the design-build contracts on Line 2 and we assisted DMRC in tender evaluations and contract awards. We are now checking detailed designs submitted by the design-build contractors and will supervise construction of these. We will also assist DMRC in management of the project as a whole.”

“International involvement on Line 2 was required to ensure employment of the latest tunnelling methods,” explained Mangu Singh, Chief Project Manager for Line 2. “Several cities in India are considering new metros but the only experience to date has been the Kolkata Metro.

That project encountered well-reported problems. So for Delhi we had to improve on all aspects of the process.”

Nine groups pre-qualified for the Line 2 design-build contracts. Three proposals for the bored tunnels contract MC1B and two for the MC1A open cut contract were received in February 2000. “All five technical proposals were accepted,” said Singh, “but the financial bids were all considerably higher than estimated.” Original estimates were based on the Kolkata Metro, designed back in the early 1970s under conventional design-bidbuild contracts. Thirty years on Delhi has a much higher specification. Nevertheless, cost proposals were too high and after negotiation were reduced by various methods including the relaxation of some specifications such as allowing sheet piling instead of rigid walls to support open-cut running tunnels.

The two contracts were eventually awarded in February 2001. The 50-month MC1A package for the 4km long open cut section with a contractual end date of July 2005 was awarded to the KSHI JV between Kumagai Gumi (Japan - Leader), Skanska (Sweden), Hindustan Construction (India), and Itochu Corporation (Japan), with contract engineer Maunsell (Australia). The 60-month MC1B package for the 6.5km long bored tunnel section from ISBT to Central Secretariat was awarded to IMCC comprising Dyckerhoff & Widmann (Germany - Leader)

the 900-1,200m rock section was also possible but again the length is too short. The options were just uneconomical when compared to open cut.”

During the TunnelTalk tour of Line 2 in December 2001, KSHI had started necessary traffic and utility diversions ahead of open cut excavation, and sheet piling had started. Diaphragm walling for two of the four stations as well as core excavation was due to start in February 2002. Work will progress 24hr/day, 7 days/week with restrictions on muck haulage at peak hours and there could be no sheet piling from 9pm to 6am. Under further contract considerations, all sites are within 2m high hoardings; muck disposal routes are identified Two EPBMs assembled for launch at Patel Chowk Station box by traffic police; noise, levels of generators, compressors and other machines must be limited; with Shimizu Corporation (Japan), Larsen & Toubro (India), and the cutting of trees on-site is strictly controlled.

Samsung (Korea), IRCON International (India) and contract engineer Mott MacDonald (UK). Notices to proceed were For IMCC on contract MC1B, work had also started to issued in April and May 2001, and a 39-week period of install diaphragm walls for open cut station works ahead of definitive design started on-site in October. core excavation and TBM launch. Project Leader Sternath

Tunnel operations

To complete the bored tunnels on contract MC1B, IMCC bought three Herrenknecht TBMs - two EPBMs and a hard rock shielded machine. Delhi is built on the waterbearing silts of the Yumuna River flood plane that overlay a highly variable rock interface with 3.5 billion year old, highly weathered quartzite and veins up to 2m thick of mica schist to a compressive strength of 100-250MPa (Fig 1). At an average depth of 15m below surface, the Line 2 tunnels pass through soft wet soils beneath the water table at 4-6.5m below the surface and harder rock strata.

On MC1A, KSHI requires dewatering between sheet piled retaining walls and shotcrete and rockbolts to support drill-blast of hard rock sections of the open-cut alignment.

Located on the Himalayan foothills, seismic loading design criteria is Category 4. Survey, monitoring, and protection measures to control settlement damage are also important concerns. The underground alignment passes beneath several protected structures as well as two of Delhi’s main railway stations.

pointed out three particular techniques being used on the project to ensure top quality construction.

First, each diaphragm wall panel is surveyed using the Koden system. An ultrasound scanner is lowered and raised slowly into the 6m long x 800mm wide x 20m deep slurry-filled trench and the profile of the wall is printed.

This allows any underbreak or fall out in the bottom to be re-excavated before the reinforcement cages are inserted. Secondly, a vertical waterproofing seal is also inserted between the panels of the permanent diaphragm walls. A PVC waterproofing membrane will seal the roof slabs of the stations.

Thirdly, the BARTEC coupling system is being used for creating links between rebar cages in the vertical walls and the horizontal reinforcement of invert, intermediate and roof slabs. A method of cold forging increases the core diameter of the rebar to take the threaded ends of the joint without reducing the bar’s cross section. No torque wrench is required and the splice is stronger than the rebar, guaranteeing full ductile elongation of the reinforcement without joint failure.

The two Herrenknecht EPB machines for Contract MC1B were first used for the Bangkok Metro in the late 1990s At Chawri Bazar TunnelTalk visited one of two small and refurbished in India, under Herrenknecht supervision, sites where access into the NATM mined station below to arrive on site in May 2002. The third machine, a new will be excavated between permanent diaphragm walls.

Herrenknecht rock machine, arrived in Delhi in January 2002 and all three were scheduled to Installing reinforcement cages into diaphragm wall panels prior to start boring in June/July 2002. concreting in contract MC1A work by the KSHI JV The TBM tunnels are lined with rings of precast concrete bolted and gasketed segments designed by Mott MacDonald. There are five segments and a key in each 1.2m wide x 280mm thick ring. IMCC has established an off site casting yard, equipped with 72 moulds supplied

by CBE of France and production is to start in March 2002.

Bored tunnelling was also an option for the open cut works on contract MC1A but as Hisayoshi Yoshikawa, Project Leader of the KSHI JV explained: “To make it worth while, tunnelling would have to be used for the full 4.5km of the contract and that would have required two of each TBM type - hard rock and soft ground.

NATM excavation of the running tunnels through

11

In accepting the challenge to meet the September 2005 opening date for Line 2, the two design-build contractors have something to prove to DMRC. Sreedharan is not fully convinced of the advantages purported by the design-build procurement method. “There are a lot of uncertainties associated with metro design and underground excavation,” said Sreedharan, “and the full risk of these is diverted from the owner to the contractor under design-build.

Different issues influence programming and decision making when design and construction are within the same organisation. Many of these risks should stay with the client in my view, but having inherited the situation when I moved to DMRC, I will have the experience of managing both conventional design-bid-build and designbuild contracts on Phase 1.”

Initial plan for NATM excavation of Chawri Bazar Station

The station is designed by Mott MacDonald as three 288m long interconnected caverns of up to 70m2, and slightly larger at fan locations, comprising twin platform tunnels and two large shafts housing ventilation plant, elevators, escalators and furnishings for concourse areas.

In addition to the logistical challenges in this incredibly crowded area of Delhi, excavation of Chawri Bazar station is further complicated by geology. A deep incision of water bearing alluvium cuts into the more competent weathered quartzite and schist right at the location of the proposed NATM station (Fig 1).

Critical paths

All three lines of the Delhi Metro Phase 1 are new rights of way, acquired by DMRC at about 8% of the project cost, using an interest-free subordinate loan from the Central and State Governments. Securing the alignments, clearing the sites and resettling displaced residents and businesses has been without incident.

“Once the Kolkata Metro was finally opened, people took to it very well,” said Singh. “Passenger numbers are high and there is little vandalism. Here in Delhi too, people have been waiting for the metro for 20-30 years. There has been a change in public attitude. A highway bridge usually takes 7-10 years to realize in Delhi, but the metro viaducts on Line 1 have been completed in 2-3 years. The metro fare is reasonably low and we are expecting up to 2.2 million commuters/day on Phase 1 when it opens fully.”

Tunnel boring on contract MC1B and rock excavation on KSHl’s open cut contract are the project’s critical paths. To meet IMCC’s 60-month MC1B contract period, an optional TBM may be specified. “We have scheduled the tunnelling with three TBMs but if necessary, we have an agreement with Herrenknecht for a fourth,” said Sternath for IMCC.

Prior to DMRC, Sreedharan was Managing Director of the Konkan Railway Corporation (p4). As a civil engineer and career employee of India Railways, Sreedharan was persuaded at 70 to remain out of retirement and take up directorship of DMRC for the crucial first years of its operation.

The Konkan Railway was procured under the Corporation’s own project management, through conventional designbid-build contracts. The same model is being used for procurement of Lines 1 and 3 of the Delhi Metro. “Designbid-build contracting on Line 1 has brought the first section to a scheduled opening in December 2002 with the remainder of the 28km line due to open in December 2003,” said Sreedharan, “and from awards of contracts in April/May 2002, design-bid-build of the 23.5km long Line 3, is scheduled to open in September 2005.” Although Sreedharan would have “preferred design-bid-build for the Line 2 contracts” the goal was to make the designbuild concept in place work.

In managing the Phase 1 contracts, arbitration through General Consultants rather than disputes review boards (DRBs), has been selected. “Arbitration is a very just and fair method of hearing grievances. We have a negotiating team in DMRC and arbitrators are appointed from an approved list for each case. It is on the performance of the owner that the success of large public works projects like the Metro are judged and on Line 1 where we have finished several contracts, we have illustrated that we will settle disputes fairly and quickly.”

Once in service, passenger fares plus advertising income is expected to repay 95% of the JBIC loan over 20 years from opening of the Phase 1 system.

The remaining 5-6% is to come from property development and the liability of any shortfall will rest with DMRC’s two Government shareholders.

For the moment, concentration is on construction.

Triumph out of tough going on Delhi Metro OCTOBER 2004

T

Shani Wallis, TunnelTalk

hings did not go exactly according to plan in Delhi.

TBM excavation at one point was inching along and was off programme by months. It was therefore with a great sense of relief that on 3 September 2004, that the last TBM on the IMCC MC1B contract broke through. The

12

6.5m diameter TBM had taken 369 days of 24/7 shift work to complete 780m of tunnel and had left behind a cutter consumption rate in excess of 1/m.

“We knew conditions on the proposed rock TBM drives would be difficult,” said Klaus Münz, of Dywidag International, who took over from Rupert Sternath as

Fig 2. Planned and actual excavation sequence for contract MC1B

of narrow alleys, are hundreds of years old, on very rudimentary foundations, of poor construction quality and practically ramshackle in condition. Dewatering in this vicinity was strictly controlled and limited by the contract documents and stringent surface settlement criteria were set. Under the lump-sum, fixed-price, design-price, design-build contract, the contractor was responsible for all geological and geotechnical risk, all third party liability, and all necessary liability insurances. The stakes were high for the IMCC (International Metro Construction Consortium) JV. IMCC celebration of final TBM breakthrough

Project Leader for the IMCC JV, with partners Samsung (Korea), L+T (India), Shimizu (Japan), and Ircon (India), “but nothing prepared us for what we met. The heavily tectonically disturbed bedrock of the Himalayan foothills region combined with the heavy weathering of Delhi’s Yumana River flood plane has created a geology of mixed hard, tough quartzite of up to 250MPa and near vertical bands of highly weathered, very weak mica schist, all hosting a high ground water table. For TBM tunnelling this presented on occasion full faces of extremely abrasive quartzite but more often the extremes of both hard rock and soft ground conditions in one face. When production was down to less than one ring or 1.2m/day and the programme was becoming critical, we consulted various experts and manufacturers to advise us on a solution but none were able to guarantee that the alternative would do any better. It has been the most difficult set of TBM excavation conditions I have experienced or heard of and I think the manufacturing industry agrees.”

When TunnelTalk visited the project for the first time in 2002, the plan was to use one Herrenknecht rock EPB TBM to excavate the 1.6km length of twin tube running tunnel from Delhi Main to New Delhi stations in three drives - mining through Chawri Bazaar Station on the first drive and being pulled through the excavated station on the second.

The two refurbished EPB machines were first on site and got off to a good start from the Patel Chowk station box in May and June 2002 respectively. “Progress through the Delhi Silt was actually quite good and we achieved an average of +6.5 rings/day for the first two drives and of more than 10 rings/day on the second two,” said Steven Meredith, IMCC Tunnel Manager. “The problem was with the rock machine drives.”

The new Herrenknecth EPB rock TBM set off on its first 100m long drive from the Delhi Main station box on 23 October 2002. Seventeen months later, in March 2004, it broke into the excavated Chawri Bazaar mined station platform tunnel after travelling just 926m in 518 24hr working days, six days/week.

“The time was spent perhaps equally between grinding through very hard, tough quartzite and struggling through mixed face conditions, passing from banded mica schist of no positive strength to very hard quartzite, and in maintenance downtime to change worn, broken, pitted Extremes of mixed face conditions got the better of the rock EPBM

At the same time, two refurbished Herrenknecht soft ground EPBMs would complete six drives through favourable Delhi Silt, first from Patel Chowk to Connaught Place stations, then from Delhi Main to the ISBT (Interstate Bus Terminal) stations at the contract’s north end for a total of 5km. Five of the contract’s six stations are open cut boxes with the sixth, under the crowded Chawri Bazaar district of Old Delhi designed as a mined NATM excavation between small surface accesses at either end.

Things began well, although activity within and underneath the Chawri Bazaar was always going to be a logistical tangle with the added challenge of maintaining the integrity of the buildings, many of which, either side 13

and flat spotted cutters. Changes were needed often after every shove, replacing on occasion up to five or more of the cutterhead’s 44 discs per each 1.2m ring,” said Meredith. “We also had two long mid-drive downtimes of eight weeks and four weeks where we undertook, in free-air, major structural repairs of abrasive ware to the machine and modification of the cutterhead, to attach grizzly bars to prevent blocks of rock entering the chamber, and to reduce the size of the openings to prevent softer wet weathered mica schist running from the face and threatening settlement of the buildings above.”

The solution

As reported in March 2002, the JV was prepared to order a second rock EPBM if, as predicted, Careful NATM work applied to excavate Chawri Bazaar Station the rock drives proved slower going than Yang invested a great deal of effort to modify the discs programmed, but as Münz explained; “there (lower the ring profile, decrease the space between the was just no time to procure and launch a second rock rings on double cutters, and improve the hub and bearing TBM. Also a new TBM investment would not provide seal designs) to get us a better cutter consumption rate on the increased production needed to salvage the the second drive - though still very high.” programme. What we decided to do was to take one of the refurbished EPBMs, after breakthrough of its second Progress was also, as predicted, little better. The second drive in June 2003, and convert it to a rock EPB machine TBM achieved an average of 1.76 rings/day just slightly by fitting a new rock cutterhead.” better than the 1.45 rings/day on the first drive. More was needed to save the programme.

Working again with Herrenknecht and with the experience of the first drive, settling on the design and incorporating upgrades and modifications from the original cutterhead NATM to the rescue as well was not straightforward. “It was a classic conflict between This came in the form of converting the short 387m B3 those who approach the task from a hard rock TBM running tunnels between Chawri Bazaar and New Delhi background and those with soft ground TBM expertise,” stations from rock EPBM to NATM excavation. A third said Münz. “The result was a compromise built on an NATM running tunnel heading was also advanced for available soft ground EPB centre piece used to ensure a some 71m towards the second rock TBM in the zero rock more speedy cutterhead delivery.” cover B2 tunnel section to recapture further time (Fig 3).

The new cutterhead arrived and was fitted in time for launch of the converted machine in the eastern B2 rock tunnel drive on 28 August 2003, long before the TBM in the first western drive ended its slow going in March 2004. The second TBM, as predicated, had the same struggle. “In such mixed conditions, it was practically impossible to operate in genuine full-plenum EPB mode,” said Meredith. “We operated more regularly with the chamber about half full.”

Cutter consumption also remained exceptionally high. To control this cost, the policy of the JV was to research supply of the least expensive, best performing cutters. “These we sourced from Korea,” said Meredith. “The supplier Dong

Chawri Bazaar Station beneath Old Delhi was already planned, designed and started as a NATM excavation but changing the running tunnels to NATM was not straightforward. A degree of ground water drainage was permitted for the station excavations but the General Consultants (GC) representing the client on the two design-build Line 2 metro contracts (a JV led by Pacific Consultants International of Japan with Parsons Brinckerhoff International, JARTS and Tonichi of Japan and RITES of India) had precluded any form of dewatering along the route of the running tunnels.

“Changing to NATM did involve risk,” said Tony Burchell, Project Director of GC, and even for excavation of the station, a 2.2m x 2.75m pilot tunnel was advanced and various tests undertaken to determine the Fig 3. Challenging conditions for 71m of NATM for the B2 drive behaviour of the ground under different methods and techniques before the contractor’s full NATM proposal was approved. “For converting the B3 running tunnels to NATM and given the NATM station experience, we permitted and insisted upon dewatering of the ground but via long drainage holes drilled ahead of excavation rather than deep hole vacuum pumps from the surface.”

Lead consultant to the IMCC design-build JV, Mott MacDonald, advanced the early stages of the NATM works but as excavation approached, the JV engaged Geoconsult of Austria to provide specialist NATM services to refine design; specify, install and monitor the necessary instrumentation; monitor the works; and provide on-site 14

engineering during excavation. “Careful and steady was the approach,” explained MI Singh Saini, IMCC’s Deputy Project Leader (NATM).

From the initial NATM shaft excavation, an 80m long drain hole was drilled parallel to, and at the same elevation as, the platform tunnels to lower the ground water. In the running tunnels, gravity drainage comprised three 6m-12m long weep holes into the faces and 21m long lateral drain holes into the outside tunnel walls. In addition, a very tight NATM excavation cycle was adopted. Top heading, bench and invert cycles were progressed consecutively on maximum 1.5m rounds with the top heading a minimum 5m ahead of the bench for an effective stagger, and the invert closed within 30m of the top-heading face or earlier in weak strata.

Further to this, 6m long forepoling on close centres and with long overlaps were installed where necessary. A dumpling left in each top-heading provided stability as well as crown access for installing the wire mesh and lattice girder support, and shotcrete was used to seal suspected unreliable faces during the support cycles.

While these measures are regularly associated with softer ground NATM excavation, not all in the Delhi tunnels was soft. Blasting was needed to excavate the hard quartzite in extreme mixed face conditions.

Through all, three full time geologists mapped every face of advance for review by the two on-site NATM engineers from Geoconsult. Real time readings of installed instrumentation, including horizontal inclinometers, pressure cells, strain gauges, and electrolevels, were also recorded, with the computer server sending out an instantaneous mobile phone message to 25 senior engineers and project managers should readings exceed the 25mm emergency trigger. This night-shift facility was never activated but cumulative settlement over the course of the two B3 drives did reach between 30mm and 40mm maximum. This was due, according to Saini, almost equally to the affects of draining the water table and to excavation deformation. “There were a few instances of weak material dropping from the crown but never a major event of crown or face fallout.” A significant achievement on the contract here in India is that there was no serious injury or fatality caused as a direct result of excavation activity.

The only event of mishap was on the rock TBM drive when the machine is suspected of having encountered an old unidentified water well. “Along with unidentified wells, there are also unrecorded basements and extensions to basements,” said Meredith. “The NATM work encountered one of these unidentified wells but it was backfilled and the forepoling avoided any kind of ground loss. On the TBM there was no forewarning. Once surface settlement readings and TBM operation gave indications of what was happening, residents of a home directly above were temporarily relocated.” Unfortunately the old home structure was damaged beyond reasonable repair and a new home has been built for the family on the same spot and at the contractor’s expense.

Positive ending

When TunnelTalk joined celebrations of the last TBM breakthrough into the short section of B2 NATM running tunnel, there was relief all around. “With this breakthrough, this is the end of excavation on our 7.9km long contract. We are very happy that it is over, even at

Dr Sreedharan, Director of DMRC, shakes hands with Tony Burchell, Director of General Consultants (left), and Klaus Münz, Director of the IMCC JV (right), at the final TBM breakthrough

a much higher cost for the rock tunnels than originally estimated,” said Münz.

Breakthrough marked the end also of all excavation for Line 2. IMCC and its counterparts, the KSHI JV on the adjoining 4km of cut-and-cover subsurface alignment, are now working towards completing construction of the full 11.9km long, 10 station Line ready for an earlier revenue opening date (ROD) than the planned January 2006 and March 2005 dates respectively. Despite facing difficulties of its own on the cut-and-cover works, the 50-month KSHI (Kumagai/Skanska/Hindustan/ ltochu) JV’s MC1A contract will meet an ROD five months earlier than planned in November 2004 while IMCC is working towards having its 60-month MC1 B contract open to the public seven months earlier than planned in June 2005.

When asked how could this possibly be achieved, DMRC (Delhi Metro Corporation) Managing Director Sreedharan said: “It is all a matter of working as a team and of being fair and reasonable. We have been sympathetic to the problems faced by the contractors and we, with our General Consultants, have made every effort to help were we can. The contractors have then responded positively in return.” The fact that these are lump-sum fixed-price design-build contracts and have hefty liquidated damage clauses for late completion might also have a substantial bearing on their progress through major programme delaying problems.

Once the 70km network of Lines 1, 2 and 3 is fully opened by the end of 2005, another 75km to extend these lines, mostly elevated and at grade, is planned to be in operation by 2010 for when Delhi hosts the international Commonwealth Games.

Prior to that, IMCC is finishing its MC1B contract. This includes erecting rings of the proposed rock EPB bolted and gasketed precast concrete segmental lining to finish the NATM running tunnels. These rings were erected using a purpose built stand-alone segment erector, designed and fabricated by a supplier in Mumbai and mounted on the back of a truck. The segment rings stood freely until the annular grout and proof grouting secured them.

15

Rock bolts were not used as part of the NATM support regime. “Their use would have been limited in such variable mixed conditions,” explained Saini. “Only Swellex might have provided some benefit but the benefit against the cost of installing them would also have been limited.”

Shotcrete was used extensively for immediate support.

“Steel fibre was not needed to provide that early tensile strength advantage,” said Saini. “We installed wire mesh as a better form of reinforcement in this mixed geology.

The Indian crews were also more familiar with wire mesh and have confidence in its application.”

Compressed air, as an aid to NATM excavation or as the controlling mechanism for a slurry TBM alternative, was not considered viable. “The risk of blowout beneath the shallow cover and escape of air through old unidentified wells would be too great,” explained Meredith. “As it was, we had escape of rock EPBM conditioning foam into a deep basement and up to the surface on three occasions and had to monitor carefully the working pressures through the mixed face conditions.”

A stand alone erector builds segments to line the NATM running tunnels

The ability to pull the cutterhead back from the face by a certain degree is a facility that Meredith and Münz agreed would have been a useful addition on the rock EPB machines.

Delhi Metro meets Games target OCTOBER 2010

T

he first winner of the 2010 Commonwealth Games in India is the Delhi Metro. It had promises to keep as part of India’s moment in the international spotlight, and where the Games’ organisers have fallen short of expectations, deadlines for the metro, set back in 2003 when the venue for the 2010 Games was announced, were, for the most part, met. The final section was inaugurated with only hours to spare, but efficient metro services to 10 of the 11 Games venues as promised were delivered by the publicly owned Delhi Metro Rail Corporation - DMRC. The Airport Express Rail Link did not make it. Awarded as a private PPP concession with the civil works managed by DMRC, the civil works of the 22.7km line, with about 15.7km underground in TBM bored running tunnels, NATM work and open cut stations, were complete but testing of the trains and operating systems missed the mark. Otherwise, metro services to 130 stations on a total 153km system were in operation, the last 15km underground link opening at 8am to provide services to the Jawaharlal Nehru Stadium for the spectacular opening ceremony that evening.

Some 1.5 million passengers/day are riding the system during the Games and patronage will remain high once the international visitors leave. The metro is a prized social and environmental service to the wide spread metropolis and its heavily congested traffic corridors.

Remarkably, the 124.63km system in Phase II of the system has been built and commissioned in little more than seven years, the same seven years that organisers had to prepare for the Games. This includes about 31 km built underground in TBM bored running tunnels, lengths of cut-and-cover alignment, and in NATM mined work. “The original deadline set by the Government for the completion of the Phase 2 lines was March 2011,” explained Anuj Dayal, Chief Press

16

Some 153km of the metro system was in service for the Delhi Commonwealth Games deadline

Officer for DMRC. “When the Delhi Commonwealth Games were announced in 2003, the deadline was moved forward to September, 2010, a deadline that was for the largest part met. A total 14 TBMs were working on Phase 2 at the same time and undoubtedly, more than a hundred contracts, on six separate metro corridors, were progressing simultaneously.”

Once the Airport Link is commissioned, the full system will comprise 189.9km with some 43km underground - 11km on Phase I and 32km on Phase II. Where three TBMs were used on the Phase I underground section, a total 14 machines worked on the bored running tunnels for Phase II and the Airport Link during the peak of civil works in 2008 and 2009. Added to this, are long lengths of cut-and-cover construction and sections of careful NATM excavation with the largest percentage of the network on elevated trackway and stations. Most of the underground stations are open cut excavations with a particularly tricky NATM mined station on Phase I beneath the crowded Chawri Bazaar district.

Geological conditions for the underground works were highly variable. Delhi is built on the banks of the Yamuna River where water-bearing silts overlay a highly variable top of rock weathered quartzite interface and random outcrops of 100-250PMa mica schist, all under a high water table. The mixed conditions favoured EPB excavation and pipe-umbrella pre-excavation supported NATM excavations. TBMs used on the project included Herrenknecht EPBMs and EPB machines supplied by Robbins, built in cooperation with Mitsubishi Heavy Industries of Japan at the Robbins facilities in China.

The first TBM breakthrough for Phase II Metro extension occurred in May 2008. The Herrenknecht machine broke through at Hauz Khas after completing a 1,450m run on the Huda City Line. The TBM was used previously on the first section of bored tunnels on Phase I in the centre of the city and by the same JV, led by Dywidag International. The second reused Herrenknecht TBM completed the parallel running tunnel to Hauz Khas.

Rock trap

As on Phase I, hard rock stumped an EPB drive on Phase II for the JV of Continental Engineering Corporation (CEC) of Taiwan and Soma Enterprise of India. The JV worked with two Herrenknecht and two Robbins EPBMs on its 7.3km long Huda City Line contract from Central Secretariate to Haus Khaz. It was one of its Herrenknecht machines stopped in its tracks by a outcrop of rock covering just less than half of the face area on the left side.

Of all the options, a change of cutterhead was selected as the most time and cost effective solution. After sinking an emergency shaft in a limited patch of ground over the TBM and alongside a main road, the soft ground cutterhead was replaced with a rock head fitted with disc cutters. Sourcing the spare rock head in Hong Kong and sinking the shaft cost the contract several months and a significant cost claim, but the plan had the drive finished successfully and in time for hand over to the M&E and track work contractors to meet a line opening in September 2010, well in time for the Commonwealth Games in October. CEC has gone on to win the first underground line contract for the Bangalore Metro (p21).

Another four Herrenknecht EPB machines were delivered from the company’s new assembly center in Chennai, to the Ital Thai Developments ITD/CEM JV for its Phase II Delhi Metro contract.

Airport Link

Three tunnelling contracts built the civil works for the Airport Link. Two Herrenknecht TBMs bored the 3.7km of alignment for the Alpine Mayreder/HCC/Samsung JV and another two EPBMs were used by the Shanghai Urban Construction Corp/Laren & Toubro JV for the 1.7km of bored tunnels and 800m of cut-and-cover work into the airport. In between, the Alpine Mayreder/HCC JV built a 2.6km section of 10m diameter single-tube, double-track NATM work, buying a new Atlas Copco jumbo for drilling in pipe-umbrella pre-support and assembling a shotcrete mobile on a track flatbed.

The 65km Phase I scheme with about 13km underground, was completed between 1998 and 2006, and closed out at an estimate of Rs.10,571 crores or about US$2.35 billion in 2012 exchange rates. Construction of the 125km Phase II network with 31km underground is estimated at about Rs 20,000 Crore or US$4.25 billion.

About 50% of the capital investment is funded via loans from JBIC (the Japan Bank for International Cooperation) with the rest allocated from national and state Government revenues. The fare box and advertising revenues cover operations and maintenance. Loan amounts and interest payments, to the value of Rs 567.63 crore or some US$125.45 million, have been paid to the Japanese funding agencies by 2010.

Through the construction Phases, DMRC has had general advisory services from a JV of Pacific Consultants International of Japan, Japan Railway Technical Services, Tonichi Engineering of Japan, India’s RITES rail authority, and Parsons Brinckerhoff of the USA. The Corporations’ Managing Director Dr E. Sreedharan however maintained a direct hands-on management style. Sreedharan credits this in large part with meeting the Commonwealth Games deadline.

When TunnelTalk met with Dr Sreedharan in late 2008, he expressed his preference for the design-bid-build method of procurement but design-build was adopted for two underground construction contracts on Phase I and for most of the Phase II construction to compress the civil works into a seven year programme to meet the promised Commonwealth Games deadline in October 2010. Sreedharan however remained closely involved with decision making and problem solving, including the solution for the EPBMs stalled by the rock conditions.

From left: 17 TBMs, cut-and-cover work and careful NATM advance have all been deployed on Delhi Metro Phases I and II

17

Association with the Airport Link was a different procurement method again. The estimated US$900 million project was awarded as a PPP concession to the Reliance Energy- CAF Consortium of Spain to build, own and operate the line for 30 years. DMRC was appointed to manage the civil works and hand them over to Hong Kong’s MRT (Mass Rapid Transit) Corp, which was contracted in turn to procure, install, test and commission all the M&E systems and rolling stock.

Civil works were handed over in early 2010 and the systems are all in place, but the operating safety clearances could not be secured in time for the Games. It was hoped that the line would open at the end October 2010 but it is disappointing that it missed the deadline. It was a flagship project specifically for the Games but that baton passed instead to the Metro itself, with its lines in services on time.

Problems however were not confined to the underground works. A major accident occurred in June 2009 when a section of elevated line collapsed killing six and injuring many others. Sreedharan accepted responsibility for breakdown of quality and safety procedures as the root cause of this worst ever accident on the project, and tendered his resignation but this was rejected.

Sreedharan remained in place to see the project through to the October deadline, but he said that he will retire at the end of this year. He was persuaded out of retirement at the age of 72 to take on the Managing Director post of DMRC in 2002 and was convinced again to stay on at the end of Phase I to manage Phase II, but at 78 this year he announced his retirement once Phase II was completed and the Games are over.

In an interview, Sreedharan, who is known as ‘Metro Man’ in India, said that integrity is the principal requirement for successful management and realisation of mega projects.

Firm but fair is how he described his interaction with the many hundreds of contractors and project suppliers he has worked with. His integrity and dedication to the job has been recognised several times with several awards of distinction.

These include a Lifetime Achievement Award bestowed by the TAI Tunnelling Association of India in 2022. When Sreedharan did retire in December 2011 he was succeeded

by Mangu Singh who had worked with Sreedharan in the DMRC since its inception. Singh is credited with overseeing the rapid rollout of Phase III of the Delhi Metro and start of the current Phase IV. Singh retired from post in March 2022 and is succeeded by Vikas Kumar. Singh is a founding member and current President of the TAI. As well as managing implementation of the Delhi Metro, DMRC offers its expertise to manage or advise development of mass transit systems in other Indian cities including Bangalore, Mumbai, Hyderabad, Chennai, Kochi, and Pune and for extensions to the system in Kolkata and a high speed rail link to the airport in Hyderabad. Overseas, DMRC is a consultant to plans for a mass transit system in Jakarta, Indonesia. In the meantime, there are plans also for Phases III (112km) and IV (108.5km) in Delhi to be completed by 2015 and 2020 respectively. The network will then span more than 413 route kilometres with more sections to be built underground.

At the end of the Phase II works there are a number of highly skilled and experienced TBM operators and tunnel workers who are now searching for new employment positions.

From left: A new Atlas Copco jumbo for drilling for pipe umbrella pre-support installation and a mobile shotcreting robot deployed for NATM work on Phase II

Delhi Metro Phase III completes TBM excavation FEBRUARY 2017

W

hen Phase III of the Delhi Metro network was approved for construction, it more than doubled the amount of underground alignment of Phases I and II combined with more than 41km and 28 stations on the total 140km and 92 stations Phase III expansion aligned underground (Fig 4 and Table 2). A total of 35 TBMs, 20 of them operating simultaneously, were used to complete the near 40km of twin tube bored running tunnel sections for 80km of TBM work in total, along with sections of cut-and-cover work and NATM mined headings for underground stations and cross passages.

All eight Terratec Phase III machines are EPBMs 18

With close of construction of Phase III in early 2017, DMRC finalised excavation on one of the largest urban

Fig 4. Extent of the Delhi Metro network to end of Phase III

tunnelling projects in the world at the time.

As part of Phase III, the first simultaneous TBM breakthrough in India was achieved by the HCC/Samsung JV when its pair of 6.4m diameter Herrenknecht TBMs on Phase III contract CC-34 broke through into Dabari Mor Station in August 2014 to complete parallel 1,150m drives from Janakpuri West Station. The machines were then transported to Dashrathpuri Station from where they advanced back into the opposite headwall at Dabari Mor Station. HCC/Samsung was awarded the contract by Delhi Metro in February 2013.

In addition to the 5.8m i.d. running tunnels, project scope includes construction of three stations.

It was for Phase III that Terratec TBMs were introduced Table 2. Scope of each of the Phases of expansion to India. Among the machines applied on Phase III, and Mandi House (Contract CC-01), was awarded to the eight Terratec EPBMs completed 20 drives, for a total Prabibha/CRFG JV. It completed the last of its four drives, length of 18km on four separate contracts. In addition to using two Herrenknecht EPBMs, in 2013 and the section providing the largest number of new machines for Phase was opened to service in June 2014.

III, Terratec also provided on site services to support the operation and maintenance of the equipment. Two The 3.25km-long central section between Mandi House of these TBMs made a double breakthrough, marking and Jama Masjid, including cut-and-cover stations at the end of tunnelling works on the 58.6km Phase III ITO, Delhi Gate and Jama Masjid (Contract CC-05), was Pink Line. Indian contractor J Kumar Infraprojects, awarded to the L&T/SUCG JV, which procured three working with China Railway Third Group (CRTG), TBMs – two from Mitsubishi and one from STEC – to achieved the breakthroughs on Contract CC-24 having completed the final 970m long running tunnel drives between Vinobapuri and Double Terratec TBM breakthrough celebrations for the Phase III HCC/Samsung JV Ashram Stations.

Another two 6.61m diameter mixed rock/EPB Terratec shields completed 2.2km of tunnels from Mayapuri to Delhi Cantt on the second Pink Line 7 CC-20 contract for the J Kumar/CRTG JV, and the HCC/Samsung JV used two 6.52m diameter EPBMs on contract CC-34 on the Magenta Line 8, which forms the most westerly section of the new line between Janakpuri and Palam Station.

The Phase III Line 6 Heritage Violet Line was split into three contracts.

The southern tunnel section between Central Secretariat shaft and Mandi House Station, including construction of cut-and-cover stations at Janpath 19

complete a total of six drives through difficult mixed face geology. About half-way into the drive the STEC TBM broke down and required a recovery shaft in front of Golcha Cinema. After more than two years of zero progress, that machine was extracted and repaired to relaunch from a shaft at Delhi Gate Station and complete the drive back into the recovery shaft.

Two 6.61m diameter Terratec rock/EPB shields were used on the Contract CC-07 of the Violet Line 6 by JV Metrostroy of Russia and local firm ERA Infrastructure. The machines encountered unexpected amounts of full face very hard and highly abrasive quartzite of up to 200MPa, and sections of highly variable mixed face conditions with numerous large diameter boulders.

Phase IV and beyond As the extensions and new lines of Phase III were being finalised and coming into service, DMRC was planning and awarding contracts for the more 100km Phase IV programme with more 40km aligned underground. Of the total 65km of the new Silver Line 10 and the extensions to the Pink Line 7 and the Magenta Line 8 currently under construction for Phase IV, 7.8km of the Magenta Line and 19km of the Silver Line are underground.

The underground sections of the Phase IV priority lines are being progress under five contracts: two to Afcons Infrastructure, DC-05 for 5.7km of twin running tunnels and six underground stations and DC-07 for 7km of running tunnels and three underground Stations on the Magenta Line 8 and Silver Line 10 respectively; DC-06 to HCC-VCCL JV for 2km of twin running tunnels and one underground station on the Magenta Line 8; and Silver Line contracts DC-08 to J Kumar for 6km of twin running tunnels and four underground stations and DC-09 to L&T for 7km of twin running tunnels and four underground stations.

Following its contract award in 2020, the HCC-VCCL JV achieved the first TBM breakthrough for the Phase IV The first of four Robbins EPBMs for Afcons for the Delhi Metro Phase IV programme at the Robbins Gurgaon factory acceptance test in March 2023

20

programme on the Magenta Line extension in December 2021. The same refurbished Terratec TBM completed the parallel 1.4km long drive in November 2022.

For its two Phase IV contracts, Afcons is using four 6.65m diameter mixed face Robbins EPBMs and four Herrenknecht EPBMs, two from each manufacturer on its two DC-05 and DC-07 contracts for the Magenta and Silver Lines respectively. The first machine to launch for Afcons was a Robbins machine refurbished at the Robbins Gurgaon factory near Delhi in early 2023.

The first TBM launched on the Silver Line 10 project in March 2023 was the first of four CRCHI EPBMs being used by L&T on contract DC-09. The machine also the first to achieve a Silver Line breakthrough in November 2023 after completing its first 1.3km long drive in eight months.

With the three priority projects of Phase IV scheduled to be in operation in 2026, the future of the additional lines in the Phase IV programme as well as plans for additional build out phases of the Delhi Metro await announcements from the DMRC and its Central Government and State Government stakeholders. n

Bangalore Metro Shani Wallis, TunnelTalk

The Metro brings a welcome alternative to travelling the congested surface streets

P

lanning for a mass transit metro system for Bangalore began in the early to mid-2000s with construction of the Phase 1 network with underground sections beneath the centre of the city starting by 2010. During the metro system development TunnelTalk visited the project to report on the progress and experiences of building the underground sections of Phase 1 in 2010 and of Phase 2 in 2022.

Phase I underground works comprise the city centre sections of the north-south Green Line and the east-west Purple Line. These form the core of the metro system buildout and today the underground sections of the operating metro represent the most wonderful public funded gift to the users, offering a clean, quiet, efficient, air-conditioned, inexpensive (just minimal rupees per journey), public transport alternative to the chaotic congested din of the street traffic options.

Today the north-south Red Line is under construction, adding another 14km of underground alignment to the network, and an elevated line to connect the city to its distant international airport is progressing.

During the visit to the BMRC, Bangalore Metro Rail Corporation, in early 2022, Subrahmanya Gudge, Chief Engineer for BMRC for the UG1 underground works southern section of the Phase II Red Line, talked about the experience of underground planning and construction in Bangalore.

He explained that, despite the struggles - and there

Table 1. Phase II underground construction bid details. Despite increasing costs, underground for new Phase II works is still the most economical and much less than surface or elevated land acquisition costs Total cost quoted by tenderers (in INR crores) BMRC estimated cost Larsen & ITD Cementation ITD Cementation - AFCONS HCC Company (in crores) Toubro India Gulermak JV Infrastructure

Package 1 Package 2 Package 3 Package 4

1624.5 1329.14 1299.24 1790.04

1684.35 Not quoted 1344.37 1771.25

Not quoted 1428.08 Not quoted Not quoted

1526.32 1342.82 1315.5 1783.76

Not quoted 1862.02 Not quoted Not quoted

1262.32 1130.6 1105.41 1549.41

21

have been many - going underground in the city centre is the least expensive option. “The current Red Line runs north south directly beneath the commercial business district of the city, beneath the streets of some of its most expensive real estate and buildings, including Brigade Road and Commercial Street. Acquiring the rights to build the metro on the surface or on elevated structures would be many times more expensive than taking the infrastructure underground,” he said. “For the cost of construction alone, elevated or surface is less expensive than the 170 Crore INR (US$22.6 million)/1km of single tube tunnel we are paying for the underground option, but it is the cost of the space and the disruption caused that inflates the surface option in a city centre. Overall, our underground metro system civil works, including stations, is costing about US$60 million/km. Including the cost of electrical and mechanical installations, the total is about 7,500 Crore or US$1 billion for 13.89km of twin tube underground alignment with 12 underground stations.”

There are several further advantages of underground versus elevated or at-grade alignments: • There are life cycle maintenance and operating operating cost savings; • The environment is more comfortable for passengers in all weathers; • The surface space is preserved for living and leisure rather than infrastructure; • It avoids the ill-effects of creating surface barriers; and • Avoids the holding of ambient heat and the trapping of air pollution under elevated structures.

Eng Gudge has worked for BMRC in Bangalore since the start of the first phase of construction in 2007. At that time,

several others in his current team worked for the General Consultant, a JV of consultants RITES-OC-PBI-SYSTRA, engaged by BMRC to manage the underground works. At that time, Nigel Butterfield of the UK was the underground works Project Manager for the General Consultant and its duties included bidder evaluations, site supervision and change-order and claims management. For the second phase, BMRC incorporated the previous role of General Consultant into its own management teams, providing a direct link between client and contractor.

“The new management structure is working well,” said Gudge. “We carry out the client management role with good experience from Phase 1 and have the abilities and team members to fulfil the role. As an industry standard in India, we award contracts to the L1, lowest of the bidders. For the four contracts of these Phase 2 works, we had up to five bidders for each. For Phase 2 bidding, the competition had become more intense, and prices have risen significantly. Initial bids for the Phase 2 contracts were all above our estimates and a second round of bidding was required. Also, where there would be a split of 30 or 50 Crore between the L1 and L2 lowest bidders on Phase 1, the split now is much more for the Phase 2 contracts. Overall construction of the 8km of twin tube underground works on Lines 1 and 2 of Phase 1 cost around 2,300 Crore. The current estimate for the 13.89km of twin tube underground alignment for Phase 2 is 7,500 Crore (US$1 billion).”

Still, all in all, underground is the most economical option under the city centre with the experiences of the Phase 1 and Phase 2 underground works establishing the foundation for future underground extensions to the city’s metro network.

Slurry versus EPB for battling through tough conditions MARCH 2014

T

Shani Wallis, TunnelTalk

he first ever, large diameter slurry TBM application in India has proven its worth in the city of Bangalore. Working through the interface between fresh and weathered granite layers beneath soft wet residual soils at the surface, the two 6.5m diameter Hitachi Zosen slurry TBMs procured for the project completed the final drives under 23 sets of tracks at the main railway station. This completed 5.1km of hard won running tunnel excavation between open cut stations for the first section of the city’s underground metro alignment.

At the breakthrough ceremony, Managing Director of the Bangalore Metro Rail Corporation (BMRC), Pradeep Singh Kharola, and Chief Engineer for the design and underground works, NP Sharma, were joined by Nigel Butterfield, Manager of BMRC’s General Consultant, the RITES-OC-PBI-SYSTRA JV, in congratulating the contractor, CEC of Taiwan, and its Indian subsidiary CICI and JV partner Soma. “The ground conditions and the logistics here in the centre of Bangalore are very demanding,” admitted Kharola. “CEC has completed the UG2 contract’s running tunnels to a high standard and quality.”

From left: BMRCL Managing Director Kharola (second from left) and Chief Engineer N P Sharma (third from right) and Nigel Butterfield, General Consultant JV (third left) commending Chris Reeves (first left) and members of the CEC-SomaCICI JV for their work; Tidy tunnelling by the CEC-Soma-CICI JV in Bangalore

22

Mixed conditions from hard rock to wet sands

“We specified closed face TBM technology for the tunnelling,” said Chief Engineer Sharma, “to control ground excavation and surface settlement, and left the selection of the actual system to the contractor’s preference. The slurry technology used by the CEC team has worked very well in the extreme mixed face geological conditions at the tunnel horizon.”

The CEC-Soma-CICI JV was awarded the UG2 contract in March 2010 for a contract price of about US$216 million and selected two 6.5m diameter slurry TBMs from Hitachi Zosen for the 5.6m i.d. running tunnels with separation plants for each also from Japan. These were the first Hitachi Zosen TBMs and the first slurry TBM systems to be used in India.

“The mixed conditions were very difficult for TBM operations,” explained Chris Reeves, Project Leader for the JV. “Our TBM operators from Thailand, with local labourers and under the leadership of Tunnel Manager Wichien Conjaisue, were able to maintain tight control of the slurry excavation process.” The TBMs operated at a relatively shallow depth of one to two machine diameters, and at an operating pressure of about 0.2-0.7 bar, always less than 1 bar, with only the upper layers of residual soils and the weathered granite matrix requiring pressurised slurry face support.

During TBM advance, heavy wear of the tools was caused by the highly abrasive granite and discs, hubs and bearings were broken as they made contact with hard bedrock. Interventions were under compressed air or in free air in safe havens of grout injected blocks installed from the surface.

Behind the TBMs, 1.5m wide rings of rebar reinforced segments, with spear bolts on the longitudinal joints

BMRC Managing Director N. Sivasaila (centre) joined the factory acceptance testing of the Hitachi slurry TBMs in Japan

and dowels on the circle joints, were installed by mechanical erectors. The composite EPDM/hydrophilic gaskets and clean build of the rings by the experienced crews, made for a high quality finish to the segmentally lined tunnels.

Over the course of the twin 5.1km long drives, the machines had to be lifted and relaunched at each of the four station boxes. “We had three launches and three retrievals for both machines,” explained Mateo Pagsisihan, Planning Manager for the JV. “For all drives we were able to leave the treatment plants in the original set up location, with the slurry circuit extending for up to about 3km at most.”

Adding to the geological and logistical challenges, the final drives of the twin tunnels had to pass under the 23 sets of tracks and platforms at the Bangalore Central Railway Station. There was little opportunity to sink investigation boreholes and the owners and operators of the station were reluctant to allow any access or disruption to train services. This did cause an incident.

While passing under the tracks on the last drive, the TBM hit a pocket of wet fine running sand that ravelled fast. The TBM kept moving and it was after setting two or more rings that a sinkhole appeared on the surface above the shield, behind the cutterhead. This was quickly filled and stabilized by the JV tunnelling teams.

The rail operator then agreed the installation of lateral support beams under the tracks above the tunnel The east-west line had to take the twin running tunnels under the 23 sets of tracks at the appraches to the Bangalore main railway station

23

alignment to ensure no disruption of train services during the remainder of the drive.

Slurry TBM technology was not the easiest excavation method nor the cheapest admitted Bob Moncrieff, TBM consultant and adviser to CEC, but it was the best solution.

“It would have been very difficult to maintain the necessary face pressure using an EPBM,” he said. “The Hitachi machines were selected for their robust design, installed power, and efficient slurry circuit pumping and running cost. Also for the location of the crusher on the slurry circuit outside the excavation chamber. They have performed well in these very particular ground conditions.”

Work on the 174-week contract started in March 2010 and was due for completion by September 2013. Due to various constraints, including delayed access to site, an extension of time was granted to complete by December 2014. Tough TBM tunnelling conditions also slowed top advance rates of 8-10 rings/day in full faces of residual soils or soils and weathered rock materials, down to two or three rings/day when grinding through faces of hard, dry massive rock. The slurry system was vital in both situations, providing a cooling effect on the TBM when working at full power as well as assisting to reduce wear through the lubricating effect of the polymer based slurry. Work on the underground station fitouts and other works were reported as on track to meet the December 2014 end date.

CEC and its CICI subsidiary is working with two Robbins EPBMs on an underground contract for the Jaipur Metro and in Delhi on Phase III of the Metro using two Herrenknecht EPBMs.

Getting Bangalore Metro back on track JANUARY 2016

Peter Kenyon for TunnelTalk

Nearly five years after signing the UG1 contract for delivery of the north–south underground section of Phase I, progress was finally reaching the last breakthrough of four TBMs into the central Majestic Station and interchange with the completed east-west UG2 contract. Land permission delays outside its control, a broken cutterhead suffered by one of the machines and the difficulty of driving EPBMs through high groundwater and mixed-face geology all played their part in delaying the contract.

Project owner BMRC engaged the Coastal/Transtonnelstroy (TTS) JV to excavate the total 5km x 5.6m i.d. running tunnels of Contract UG1 in April 2011 and the 707.9 crore INR (about

US$160 million) design-build contract should have been delivered in three years, by April 2014. The JV however has struggled to complete tunnel excavation and the first breakthrough at Majestic Station was by the CEC-Soma-CICI JV east–west UG2 line contractor, using one of its two 6.5m diameter Hitachi Zosen slurry machines.

Unlike the Hitachi Zosen slurry TBMs, the Coastal/TTS JV chose EPB technology for excavation of the north–south contract. Two 6.45m diameter Herrenknecht EPBMs were procured to complete three twin tube sections of about 1,500m each, to link two underground stations from the south to the interchange at Majestic Station, and a Seli EPBM for the twin 950m-long drives from the north ramp to Majestic Station (Fig 1).

A difficult mixed ground geology comprising hard granite and soil, high groundwater levels, and problems associated with tunnelling near the weak and shallow foundations of historic buildings all contributed to slow progress.

The two Herrenknecht machines launched out of the south ramp in October and November 2012. Launch of the Seli EPBM was delayed almost a year over a land procurement dispute that went all the way to the India High Court. Launch was delayed to June 2013 some 26 months into the 36 month underground works contract.

By early 2016, 39 months since launch, neither Herrenknecht machine had made final breakthrough into Majestic Station. TBM 1 began its final of three drives in February 2015, while TBM 2 launched in December 2015 on its third and final drive.

Time spent excavating the middle 432m-long drives account for much of the delay. TBM 1 took 12 months from launch to achieve breakthrough. TBM 2 took 10 months longer to complete of the parallel drive.

Sharad Kumar, Coastal Director of Operations, told TunnelTalk: “In this stretch, both TBMs encountered huge boulders, and in one particular location concrete reinforced blocks. This seriously damaged the TBM cutterhead and resulted in a stoppage to carry out repairs under hyperbaric conditions. In February 2015, Coastal/TTS called in Robbins to assist with operation and maintenance of the two Herrenknecht EPBMs. Kumar of Coastal explained that experienced expertise was needed to cope with the difficult geological conditions. “Herrenknecht was unable to offer an operational contract due to its own policy issues, so we approached Robbins to take up the subcontracting work which they agreed following discussions with the client. Herrenknecht provided support to refurbish the

From left: First breakthrough into Majestic Station for the north-south UG1 contract by the CEC Hitachi Zosen slurry TBM; Damaged cutterhead of the Seli machine; New Palmieri cutterhead on site for the Seli EPB machine

24

machines prior to launch on the final drives and during the difficult middle drives through the boulder zone.”

Robbins has since had a field service team of more than 70 personnel on site to oversee the maintenance, repair and relaunch of both machines on their final drives. The Robbins team continues to supervise all aspects of TBM excavation, segmental lining, mucking out and grouting operations for these final drives.

Meanwhile, the Seli machine found itself in difficult ground from the start. In July 2014 it suffered a damaged cutterhead after encountering large boulders and highly fractured rock. The recovery required excavation of a 20m deep access shaft ahead of Progress on Majestic underground interchange station (January 2016) the cutterhead. After 12 months of repair work, including manufacture in Italy by Palmieri of a Phase II and IIA new cutterhead, and subsequent transportation by sea to In the meantime, Government approval has been India, the stricken Seli machine finally resumed tunnelling granted for construction of the 26,405 crore INR (about in July 2015. By early 2016 it was 300m from breakthrough US$5.28 billion) Phase 2 of Bangalore’s Metro system into Majestic Station to complete the northern section of that will add 72.1km to the existing 42km of Phase I. New contract UG1. elevated extensions will be added to all four sections of Phase I and two new lines of 18.8km and 21.2km are in Ahead of the setbacks, a decision had been taken by the Phase II plan.

BMRCL to minimise project slippage by mobilising CEC to complete the Seli machine’s parallel drive using one of its Hitachi Zosen slurry TBMs. “The decision was made well before the Seli TBM became stuck,” explained Kumar. “It should be noted that the slurry TBM also struggled for 5–6 months in the same stretch in which the Seli EPBM had suffered damage.”

As a result of the delays, Phase I of the Bangalore Metro ran two years behind schedule, and 2,200 crore IRN (US$325 million) over its original 11,600 crore IRN budget (about US$2.64 billion in 2011 prices).

In spite of the challenges faced, Coastal sticks by its choice of EPB technology. “Ultimately it was the decision of Coastal to select EPB technology, and we would not take back that decision,” said Kumar. “The machines supplied to us are world class. The stoppages were mainly due to financial challenges rather than technical problems.”

Kumar added: “All three TBMs engaged for the project, and which were designed according to the preliminary geological data made available to us, have encountered a tough geology. This was the first use of EPBMs in Bangalore and everyone should be aware that TBM performance increases as the operational team gains experience. We believe that we have learned very important lessons on the north–south drives that will help us in reducing delivery time for future underground works of Phase II of the project.”

Excavation of the UG2 east–west running tunnels by the CEC/Soma JV began in March 2010 and was completed in March 2014, inside a revised schedule of December 2014 that was granted as a result of a number of factors including delayed access to site.

A separate contract for excavation and construction of the interchange station at Majestic was awarded to the GYT/Coastal JV. Full system opening of the north-south Green Line was finally achieved through Majestic Station in June 2017.

The planned north–south Red Line between Gottigere and Nagawara includes 14.2km of underground alignment, and 12 underground stations. Phase 2A is a 23.4km elevated extension to Bangalore International Airport. Bangalore’s regional Karnataka Government and the central Government approved construction of the 6,395 crores INR (US$1,351.15 million) 42.3km Phase 1 metro system investment, in April 2006. The project is being financed by Central State Government by way of equity, subordinate debt and senior term debt.

Phase II procurement

In March 2019, the first two of four contracts to build the 14km underground section of the Bangalore Metro Phase II were awarded to L+T. The award for the central UG2 and UG3 under the centre of the city comprises 6km of twin tube running tunnels and five underground stations from Vellara Junction Station in the south to Pottery Town Station in the north (Fig 1). The 2.76km design-build UG2/UG3 of the new 21.5km long Line and the 2.8km long design-build contract are to be completed within a contract period of 42 months.

Award of the first two contract packages to L&T comes a year after proposals for the original procurement process for the 14km long underground section of the line was cancelled by BMRC. Sixteen construction companies requested bid documents and when financial bids from the four competing firms were opened the combined total for the four lowest bids was 8553.45 crore INR (US$1.28 billion), nearly 70% higher than the estimated total of 5047.56 crore INR (about US$760 million).

Total cost of the corridor was estimated by BMRC at 11,908.32 crore INR including the metro rolling stock and system M+E fitout.

The contractors CEC-Soma-CICI JV and the CoastalTranstonnelstroy JV who worked on the underground 25

sections of Phase I declined to participate in the Phase II procurement.

reached the end of its first southbound 970m drive into Majestic Station after almost three years.

Staged opening of the Phase I lines began with elevated sections in 2011. The first sections of underground system on the east-west Purple Line, either side of the delayed Majestic Interchange Station, opened in May and November 2015. Delays on Majestic Station, held up opening of the central section of the north-south Green Line and continuous travel on the east-west Purple Line through Majestic Station until June 2017.

Speaking to TunnelTalk, Coastal Director of Operations Sharad Kumar spoke candidly about the difficulties faced. “Due to severe jointing, rock chunks were continually coming loose from the face, but the cutterhead would keep on rotating without the material being crushed. This created an imbalance in the machine and ultimately the cutterhead became overexposed to high torque, resulting in high wear and tear. In the process, the cutting tools and cutter mounts, as well as the cutterhead itself, were damaged.” A 20m-deep recovery shaft was required for repairs.

Final breakthrough on the 975m drive was eventually achieved in November 2015.

It took nearly four years to complete six drives totalling 1,600m of twin-running tunnels south of Majestic; and just under three years to complete the 975m parallel tunnels to the north. The 6.5m diameter Seli EPBM finally

New line brings new experiences AUGUST 2022 for Bangalore Metro Shani Wallis, TunnelTalk

S

lurry and EPB TBMs went headto-head again in Bangalore, excavating the underground alignment of the new metro line.

For the current line, the client, the BMRC (Bangalore Metro Rail Corporation), was again reluctant to specify a method for application in the diverse, mixed geology of Bangalore for risk management reasons, specifying an excavation method exposes the owner to claims from the contractors should the specified method prove wanting.

With the selection left to the three current contractors on the new northsouth line, one has selected four slurry machines from CRCHI of China, another has selected two EPB machines from Herrenknecht, manufactured at its factory in Chennai, India, and the third has three TBMs; one EPBM and two slurry machines from Herrenknecht (Fig 3 and Table 2).

All nine machines are into their respective drives and once again the fortunes of each TBM type is mixed. Each one is struggling with the notoriously mixed ground conditions beneath Bengaluru, ranging from soft water-bearing ground to very hard Granitic gneiss bed rock and very hard Dolerite boulders, and coping with different logistical and technical issues.

Where the slurry TBMs proved better suited to the conditions on Line 1, the slurry machines on the current works are having significant troubles and, likewise, just as the EPBMs struggled on Line 2 ten years ago, the Phase 2 EPBMs are experiencing slow-going for several reasons.

26

Table 2. Nine TBMs working on the Phase 2 underground contracts Contractor Afcons

Larsen & Toubro

ITD Cementation JV

TBM Type Manufacturer Condition

Logistics

Slurry

Herrenknecht New

Loco and skips

Slurry

Herrenknecht New

Loco and skips

EPB

Herrenknecht Refurbished Loco and skips

Slurry

CRCHI

New

Slurry

CRCHI

New

Slurry

CRCHI

New

Slurry

CRCHI

New

EPB

Herrenknecht Refurbished Loco and skips

EPB

Herrenknecht Refurbished Loco and skips

MSVs (multi-service vehicles)

Fig 3. Phase 2 of the Bangalore Metro includes 14km of twin tube underground alignment with 12 new open-cut underground stations

From left: Launch of one of the four CRCHI slurry TBMs from China being used by L&T on its two package lots; Launch of one of the three EPB and two slurry TBMs from Herrenknecht being used by Afcons and the ITD Cementation JV on their Phase 2 packages

Discussions during a visit to Bangalore in April 2022, and a tour of the works, hosted by Subrahmanya Gudge, Chief Engineer; Raghavendra Shanbhag, Deputy Chief Engineer; and Ms Gowri, Assistant Executive Engineer of the BMRC UG1 Underground Works for the southern section of the project, revealed how the technology of each TBM system still has a long way to go to be truly efficient and capable of performing reliably in known geological conditions. It also demonstrated clearly some important pros and cons of each TBM type and their logistical backup systems.

In the first 30 minutes of our meeting, Chief Engineer Gudge explained the top difficulties experienced by the two TBM types. “The dolerite rock is weathered in layers like an onion from softer outer layers to the hard inner rock of up to 150-180MPa in UCS strength.

Between 15m and 20m below the surface, the alignment is at the horizon of these weathered layers and the upper waterbearing soft ground deposits. We are therefore almost constantly in mixed-face soft-hard boring conditions. For the slurry machines, there is trouble establishing a balanced pressure in the plenum to hold back the soft waterbearing ground and apply

enough forward pressure to cut through hard rock. The pressure from the ground and the operating pressure to push forward seem to be working in contradiction of each other.

“For the EPB machine,” he continued, “the mixed face conditions create the same trouble with the addition that the excavated soil fails to create an effective plug in the screw, causing discharge of very wet material whenever the screw conveyor gate is opened. Operating the EPB machines in the mixed conditions has the opposing needs of high cutterhead rotation to excavate the rock, and lower cutterhead rotation to control excavation of the soft ground to avoid over excavation and settlement of the upper soft materials. These two needs are in direct opposition to each other yet are needed in a face of mixed excavation conditions.

“With very hard rock in mixed faces, progress for both types of machines is slow and damage to the cutters is high, calling for frequent interventions. These are in free air whenever possible but under hyperbaric conditions at up to 1.7 bar pressure when necessary. For our program schedule, we estimated progress in a full

Engineers Gudge (left), Gowri (right) and Rehman (middle) of BMRC hosting the L&T drive visit, the slurry TBM and MSV combination providing for a clean, rail-free invert; Right: L&T Deputy Manager Dhananjay and the L&T slurry TBM operator explained the difficulties of excavating the mixed face conditions

27

face of soft ground at an average for both TBM types at 5m/day/machine in the two 10hr working shifts/24hr day from 7am and 7pm. In a full face of rock the programme average was set at 2.56m/day and in mixed faces it was estimated also at 2.56m/day. These anticipated averages were not part of the contracts and the balance between excavation advance and operation and maintenance of the machines is the constant vigilance and skill for the TBM operators.”

Out on site, we visited first the slurry TBM that was about 200m into its second drive from MG (Mahatma Gandhi) Road Station box to Rashtriya Military School (RMS) (Fig 1), its slurry circuit pipelines extending back through the previous 1km drive to the slurry treatment plant (STP) located at the Shivajinagar Station launch site of the two slurry TBM drives for contractor L&T (Larsen & Toubro) of India. The STP for the other two L&T slurry TBMs is at the Cantonment Station for twin drives south and twin drives north (Fig 1). Together with the CRCHI slurry TBMs, L&T mobilised MSVs (multiservice vehicles) for wheel bound delivery of segments and supplies. The MSV+slurry excavation combination made for a clean tunnel for walking the invert to the TBM. At the TBM, Suresh Babu, Deputy Manager (Tunnel) for L&T and the shift TBM operator explained that the machine was just finishing a maintenance period of about eight hours. Two disc cutters had to be changed, mainly due to being broken rather than worn. Cutter head bolts had to be tightened, and “fishing” was ongoing before TBM restart. The intervention was possible in free air and the fishing was for pieces of broken discs, broken scrapers and other cutterhead pieces from the slurry in the lower part of the excavation chamber. “The cutterheads are having a tough time in the hard rock and in mixed faces and disc breakages are frequent,” explained Babu. “The TBMs have seven x 250kV motors to deliver a 42,000kN thrust and a

maximum torque of 7,200kNm. The rebar reinforced segmental lining is fine for a 42,000kN thrust, but we are limiting thrust and torque to 26,000kN and 1,800kNm maximum respectively to avoid damaging the cutterhead.”

“We do have CRCHI technical engineers with us here in Bangalore,” said L&T Tunnel Manager Dhananjay Kumar Singh, “and the cutters and spare parts are all from China.”

Before working in Bangalore, Deputy Tunnel Manager Babu worked on slurry TBMs for the Doha Metro. “On the outside the machines in Doha and Bangalore might look the same, but there is a lot of difference,” he said. “The Doha Herrenknecht machines had a middle retraction of 200mm which made cutter changes and interventions easier. They had a middle shield articulation and a tailskin annular gap of 65mm which made navigating curves easier. The tightest curve on the Bangalore alignment is 235m radius and the machines have no middle articulation and a 35mm annular gap. The Doha TBMs had six annular grouting ports through the tailskin, the Bangalore machines have four; the Doha machines had two thrust rams for each shoe acting against the segmental lining, the Bangalore machines have only one; the Bangalore machines have fewer thrust rams on the circumference, with one ram on some shoes, making them more difficult to steer.”

As the Bangalore TBMs advance, their mechanical segment erector lifts and places the six segments and key in each 1.5m bolted and gasketed ring. After every 4th ring, the services to the slurry TBMs are extended.

For manufacture of the 1.5m wide segments, L&T is using a set of segment moulds they purchased from Herrenknecht. This is the fourth project for the same moulds – “and this will be the last,” said Babu – and the design is for inserting curved bolts. As with the lining of the first lines in Bangalore, the segments are fitted

Left top: Disc cutters on the slurry TBM drives for L&T are often replaced due to damage rather than wear in the 15m-25m deep drives; Some shoes of the CRCHI slurry TBMs have one thrust ram rather than two Middle: Segments in the ring build area where (right) the mechanical segment erector (top) lifts the segments into place for securing with curved bolts (bottom left); Segments and supplies are delivered to the TBM by MSV vehicles (bottom right)

28

Left: Slurry circuit pipes and other services pass back through the MG Road Station box to the slurry separation plant at the Shivajinagar Station box; Right: The STP system is operated jointly by the STP and the TBM operators (top); Discharge of the fine sediments beneath the slurry filter presses (middle); Tanks of cleaned and fresh slurry ready to be recycled back to the TBM (bottom)

with a combination EPDM/hydrophilic gasket supplied

by Dareyong of Korea.

As the conversations on site continued, some universal truisms were agreed: •

•

•

That rarely do those who make decisions about a contract in bidding and award end up having to work with those decision on site.

That too often decisions, particularly for purchase of high capital investment equipment such as TBM systems, are based largely on price rather than capability.

That those working on the site have to adapt to the tools provided and make the best of it, which they always do if their experience and dedication to the job is present.

we can, for the convenience of the passengers and to reserve the deeper levels for the alignments of the future.

The alignment at 15-25m below the surface is a difficult

Breakthrough for one of the L&T slurry TBMs

Taking the discussion back to TBM tunnelling, Eng Gudge explained that to go deeper with the underground alignment into a greater degree of full-face hard rock geology and away from the weathered and soft ground interface, was not an option. “For these initial lines we must stay as shallow as 29

interface horizon but we have completed extensive investigations with one core boring every 30m and additional geophysics, seismic and tomographic studies for more sensitive areas. These provide the best information we can to the bidding contractors but unlike openface excavation, TBM excavation, is an indirect method.

Operating a TBM is a white-collar job. The cutterhead of the machine is doing its job and only afterwards do you see the result. There is little the TBM operator can do to change the excavation parameters from one stroke to the next. This is pre-set before the TBM is put into action - and probing to investigate conditions ahead is difficult if not impossible. Short of getting a different machine to hope for better performance, we have to live with the possibles, not the anticipated.”

From the TBM, we walked back through the first of the two drives to the STP and visited with Ram Krishna Srivastava who ran the slurry treatment plant also for the earlier Line 1 Hitachi machines. “Basically the STP setup is the same, but with a major difference. On the first operation, the whole slurry pumping circuit was operated from the STP, including the starting and stopping of the slurry pumping system on the TBMs. Here the TBM operator manages the slurry pumps on the TBM and the STP manages the conveyancing pumps, separation operations and slurry density balancing.

Close communication between the two operators – TBM and STP – is needed but this is an easier system to work with. We have a slurry circulating flow of between 600800m3/hr. For the treatment and recycling back to the

TBM, we keep the slurry at a density of about 1.3. If it rises to 1.4 it will block the pumps. In rock the slurry to the machines needs to be at 1.2 density.”

For L&T Tunnel Manager Singh and his TBM crews - as part of a total contract contingent of 1,300 workers progress for their slurry TBMs is averaging a 2.5hr cycle – 18-19 minutes to build a ring and 30 min to excavate the next 1.5m stroke. While nursing along the four slurry TBMs on the two L&T contracts, Tunnel Manager Singh confirmed that the work will get done. “We will finish these drives,” he said “and with these machines.”

Ending the visit on high note, Damodaram Assistant Executive Engineer for BMRC explained that in the previous week, a contact best of 14 x 1.4m wide rings, or 19.6m in a 2-shift 24hr day had been achieved by a parallel drive TBM that was about 20m or so from its breakthrough into MG Road Station box. At 19.6m in a day, it was suggested that breakthrough could be the next day. As it was, five days later, on 15 April, the TBM broke through to the great celebration and satisfaction of the teams and after undergoing 200 maintenance cycles into the cutterhead plenum.

Next, we visited one of the three EPBMs being operated by Afcons of India on its drive between Vellara and Langford Town Stations. Behind its TBMs Afcons has mobilised with rail bound supply and muck trains, lifting each muck skip to the surface for discharge to the muck pile for onward disposal, which, for delivery of segments and muck trucks

From left: One of the Herrenknecht EPBMs ready for its second drive for Afcons; Afcons operator at the controls of the Herrenknecht EPBM; Loading point of the rail-bound muck skips working behind the Afcons EPBMs

30

Looking back along Brigade Road (left) to the elevated section of Line 1 at its elevated MG Road Station with cranes of the underground MG Road Station of the new line (right) behind; The green hoarding is a mobile unit that creates an exclusion zone for pedestrians and vehicles as it follows the TBM progress beneath Brigade Road

away from site, for all contacts, is only at night through the otherwise congested streets of the city.

to their company engineering departments in efforts to influence decisions on the next tunnelling projects.

Access, again down the stairway into the 20m deep station box, led to a walk along the walkway to the TBM which was into its second drive. The machine had just finished a ring build and was into excavating the next 1.4m stroke.

The thought was though, that the TBM managers and crews would learn so much more if they visited the job sites of other tunnelling jobs. Perhaps it is for the client’s management team to facilitate these open invitation visits and inter-contract group discussions. Establishing a society of tunnellers in Bangalore, as part of the India Tunnelling Society, would also provide a forum for those at all levels of the underground construction industry in the city – water, metro, road, utilities etc – to meet and share experiences, leaving their company and commercial allegiances at the door, as many members of tunnelling societies of the world do, and so many more could. Celebration of breakthroughs could also be occasions for inviting crews of neighbouring contracts to share the achievements and be introduced to each other. They are all in the same boat, facing the same difficulties towards the same end goals.

At the controls, the TBM operator shared the news that “in these conditions, the machine was not performing like a Ferrari.” It was making slow progress at an average of about 1 ring/shift.

As we watched the console monitors, wet muck gushed from the screw conveyor gate when opened onto the TBM transfer belt conveyor and back into the muck skips, making a mess, despite protective plastic sheeting, at the discharge point and the off-load into the skips. With the skips mostly full of water, the train ride uphill back to the station box was also a muddy mess for regular clean-up by the clean-up crews.

At the elevated station at MG Road, the Line 1 interchange station with the new underground station on Line 3, passengers are required to leave one station to transition to the other. Nonetheless, the new line will bring much needed added options and services for the commuters of Bangalore.

Speaking to the Afcons crew, it was surprising to know, that even though separated by only about 800m, the crews know very little, if anything, of their compatriots on the neighbouring contracts. It could be said that the interest to know what others are doing is not a priority when deep into your own job, but it is by these on-site, on-the-TBMs, on-the-job crews sharing experiences that improvements and advances can be made. The crew managers of these TBMs will be the contract managers of the next TBM projects and it is their shared knowledge that will make the differences for future contracts. Otherwise, all will stay the same, making the same selections and ill-considered decisions as always.

In discussing the point, Tunnel Mining Engineer Karthik for Afcons explained that the company does have a knowledge sharing programme, that the TBM managers and operators are invited to give reports and opinions

Segment casting works

On another day, a visit was hosted by Ms Gowri of BMRC to the casting yard of the segmental linings for the Afcons drives. The car ride followed the elevated Purple Line 1 from the BMRC Underground Division offices near Cubbon Park, east to the Indiranagar area and to a well laid out production facility where we met with Manager (Execution) Subbarayalu and Senior Engineer (QA/QC) Biswadip Mandal for Afcons and Section Engineer Varun for BMRC. “We are producing three types of segments here,” said Subbarayalu, “Type C with highest rebar reinforcement of 1.13 tonne/ring of 1.4m wide x 275mm thick segments for the areas of cross passage breakouts, we need 81 rings of this type; 3,226 rings of Type B with the least reinforcement of 650kg/ring; and 543 rings of Type A segments with 710kg/ring based on overburden and other design parameters. We also produced 210 rings of temporary segments with 380kg of reinforcement/ring for extension of two drives into the zone of Dairy Circle Station as box excavation was complete to only half its length.”

“We normally programme to have the station boxes fully excavated ready for pull though of the TBMs,” explained Eng Gowri for BMRC. “To drive through and breakout for 31

station excavation would be expensive as our stations are 200m long. Because start of Dairy Circle Station box was delayed, the mitigation was to excavate half to invert level and build the temporary TBM tunnels for the other half for later breakout and full station box excavation.”

The casting yard is equipped with stationary moulds for eight rings and eight rings are produced/day explained Production Manager Subbarayalu. “These moulds are from Korea and this is their second project. We are fabricating our own steel rebar cages on site and we have our own concrete batching plant. Casting in the moulds requires 7.5m3 of concrete per ring. This is delivered to the moulds in 6m3/truck from the batching plant. The moulds vibrate the concrete into place through the cages and the extrados is micro finished by hand to fill any pin holes or honeycombing, before the lids are closed to control the extrados shape. A rebar bending machine on site produces the 240 rebar pieces needed to fabricate the cages and we have spacers in the moulds to ensure the 40mm intrados and 50mm extrados cover over the rebar.”

In the quality control laboratory, Eng Mandal said that test cubes are cast for each ring. At 12.5MPa strength, after 15 to 16 hours (+/- 2 hours depending on the ambient temperature), the moulds are struck and the demoulded segments are covered on every surface with two coats, 10-15 minutes apart, of a water-based curing compound.

With a cube check to confirm 15MPa strength, the segments are stacked in the stockpile and at a 28-day cube check for a minimum 50MPa strength, the segments are available for shipping to site.

“After every 500 rings cast, another trial of three rings is assembled vertically to check the tolerances of the moulds

and avoid segment-to-segment lips and ring-to-ring steps,” explained Eng Mandal. “We must also check all segments to ensure they meet the contract building crack tolerances specification of 0.2mm on the intrados.”

When speaking with Eng Gudge of BMRC, a query about the use of steel fibre as an alternative to rebar cages he said that “we ran some trials for SFRC segments and there were some issues related to surface finish, so we have continued to build the metro tunnels with rebar reinforced segments.” In the casting yard, Eng Mandal said, “we use steel fibres in shotcrete in the station boxes and cross passages, with the M50 grade of concrete becoming a grade M80 concrete with the introduction of steel fibre.”

In closing the casting yard visit, it was confirmed that 3,200 rings have been cast and that the remaining 600 rings will be completed in July or August. “We will then be off to the next tunnelling project,” said Production Manager Subbarayalu. Happily, it was considered that the next project might be the start of a metro system with underground sections for the city of Agra in the north, the home of the famous Taj Mahal. “That would be a good next move,” all agreed. n

TunnelTalk references •

Slurry or EPB for conditions in Bangalore - TunnelTalk Annual Review 2015, p60

External references

• ITA-AITES Member Nation societies • Tunnelling Association of India - see p3

Left: Afcons casting yard where managers Subbarayalu and Mandal and their team conducted the tour of the facility (bottom) Middle: The segments are rebar reinforced (top) with cages fabricated by an on-site rebar bending unit (bottom); Stationary moulds vibrate to ensure efficient concrete fill around the rebar cages (right): Once struck, the segments are coated on all sides with a curing compound (middle); After every 500 casts, the mould tolerances are reverified with a new master ring set (bottom)

32

Mumbai Metro

T

structures, methods and progress

he 33.5km long underground corridor for the Mumbai Metro Line 3 runs north-south to connect the Colaba, Bandra and SEEPZ Santacruz Electronics Export Processing Zone districts with 26 underground stations and one station and the depot at the north end at grade (Fig 1). Line 3 is the first underground metro line for the city and construction was divided into eight civil contracts of which the seven tunneland-station packages were tendered during 2015 and awarded in 2016. The contractors on each package started work on site with excavation of open-cut station boxes and the procurement of the 17 TBMs needed to excavate the twin running tunnels (Table 1).

The project is being developed by the Mumbai Metro Rail Corporation Ltd (MMRC), a joint venture delivery entity of the Central Government of India and the State Government of Maharashtra.

Procurement of Line 3 is under EPC engineering-procurement-construction or design-bid-build methods. This is after disappointing results on PPP publicprivate-partnership projects in Mumbai and much the same as the Delhi Metro procurement model which has proven successful and manageable.

In December 2016, Line 3 had an estimated 23,136 crore INR cost or about US$3.4 billion and has been financed by a loan of 13,235 crore INR or US$1.9 billion from the Japan International Cooperation Agency (JICA) which accounts Fig 1. Route and contract packages for the 33.5km long Mumbai Metro Line 3 Table 1. Contract scope, value, appointed contractor and TBMs ordered for each civil tunnel and station package Package Scope Award value Contractor TBMs ordered Cuffe Parade to INR29.9 billion Larsen & Toubro and 2 x new Robbins Crossover UGC-01 Hutatma Chowk (US$444 million) Shanghai Tunnel Engineering Co TBMs CST Metro to INR25.2 billion Hindustan Construction Co 2 x new Terratec dual mode UGC-02 Grant Road (US$370 million) and Moscow Metrostroy hard rock TBMs 1 new, 1 used Robbins/NFM Mumbai Central to INR25.6 billion Dogus and Soma UGC-03 rock slurry TBMs Worli (US$378 million) Siddhivinayak to INR28.3 billion Continental Engineering Corp, ITD 3 x Herrenknecht EPBMs UGC-04 Shitladevi (US$419 million) Cementation and Tata Projects 1 new and 2 used 3 x Terratec machines: 1 new Dharavi to INR28.2 billion J Kumar Infraprojects and dual mode rock TBM and 2 UGC-05 Santacruz (US$417million) China Railway Tunnel Group used rock EPBMs CSIA to INR21.2 billion J Kumar Infraprojects and 2 x new Terratec dual mode UGC-06 CSA International (US$314 million) China Railway Tunnel Group hard rock TBMs Marol Naka to Santacruz INR22.8 billion Larsen & Toubro and 3 x STEC refuurbished TBMs UGC-07 Electronics Export (US$337 million) Shanghai Tunnel Engineering Co Processing Zone 33

Secant pile perimeter walls and steel joist beams support open cut access shaft excavation

for 57.2% of the total cost. The funding balance is made available by the Government of India and the State Government of Maharashtra/MMRDA, in the form of equity and subordinate debt, and by a 3.4% contribution from the Mumbai International Airport corporation (MIAL).

In May 2016 MMRC appointed the AECOM Asia led consortium as General Consultants for Line 3 in compliance with JICA guidelines. As General Consultants, the team, with partner consultants Padeco (Japan), LBG Inc (USA) and Egis Rail (France), has assisted MMRC in design, supervision, quality control, safety and contract management of the project. The team assisted in evaluation of bids for civil works; carried out review and proof-checked detailed designs; prepared tender documents for procurement of track work, rolling stock and system components; supervised construction; and is managing the commissioning of all system components; and preparing operation and maintenance manuals.

The geology of the Mumbai is largely hard basalt rock at up to 125MPa in compressive strength to the south and softer breccia and tuff to the north. For the most part hard rock excavations in Classes I and II are dry with groundwater ingress experienced in the fractured and jointed rock of Classes III, IV and V. Groundwater ingress, some at high volume and under hydrostatic pressures of up to 5 bar, is also experienced in mixed face conditions and through upper sedimentary overburden and in softer tuff and breccia deposits.

“In planing the project, the main underground works were grouped into seven packages of between 21-30 billion INR ($315-445 million) with between 4-6km of twin running tunnels in each package along with two or three stations and other associated works,” said Director (Projects) S K Gupta.

Of the 26 underground stations, 19 are cut-and-cover boxes of up to 250m long x 22m-30m deep, and seven, in the particularly congested areas at Hutatma Chowk, 34

Kalbadevi, Girgaon, Grant Road, Santacruz, Sitladevi and Marol Naka, are a combination of cut-and-cover and mined NATM excavation. The stations at Cuffe Parade and BKC are up to 450m long to include crossovers. The cut-and-cover station boxes and access shafts on the line are supported by secant piles with rock and soil anchors and struts providing extra support as core excavation has progressed. Excavation has advanced using controlled drill+blast, breakers and excavators.

For four of the mined stations, at Kalbadevi, Girgaon, Grant Road, Shitladevi and Santacruz, the TBM segmentally lined running tunnels were excavated through the station zones ahead of later breakout for station platform enlargements.

Mined station excavation is also by controlled drill+blast, breakers and excavators, with rockbolts and steel fibre shotcrete for immediate support. “All exposed NATM faces are sealed with steel-fibre reinforced shotcrete and grout injection is used to control local excessive water ingress,” said Gupta.

All the running tunnels on the project are designed with a 5.8m i.d. and are lined with precast concrete segments reinforced with rebar cages. Most linings have straight bolted or dowelled circumferential joints while the lining design on UGC-01 has knuckle joints on the circular segment-to-segment ring joints and are bolted on the longitudinal joints. The segments for all the contracts are produced at a concrete casting works in Wadala, about 10km from central Mumbai. Each contractor has managed the fabrication of its own segment production.

Muck haulage behind all TBM drives is by rail-bound muck cars with service trains carrying in the segments for each ring of advance. Jet grouting has assisted the breakout and break-in of TBMs in zones of softer, mixed-face or highly fractured or jointed rock conditions.

Ahead of selecting and ordering their TBMs, the appointed contractors of each package carried out additional site

TBM progress has been recorded at up to 24m/day

Acceptance test for first UGS-05 Terratec TBMs; Fifth Terratec TBM for Mumbai assembled

investigation. “This resulted in contractors ordering different types of shielded TBMs to cope with conditions,” said Gupta. “These include slurry, EPB and dual and multimode machines and all have performed well.”

The single shield Terratec TBMs are equipped to operate in either open or closed mode in the predominantly fresh and slightly to moderately weathered basalt and breccia. The hard rock cutterheads are dressed with 17in disc cutters,

Terratec contributions

UCG-02 is the first section to be completed

The supplier of most TBMs to the project, supplying seven of the 17 machines, is Terratec, delivering five new dual mode rock TBMs and two refurbished rock EPBMs. The 6.6m i.d. TBMs achieved consistent progress averages of near or above 300m/month with bests of 102m/week and up to 20m/day.

The first two of the seven Terratec TBMs were dispatched to India following successful factory acceptance tests in China in August 2017. The first of these is the first of two new 6.68m diameter dual-mode hard rock TBMs that will be used by the HCC/Moscow Metrostroy JV to build the 4.049km twin tunnels on the UGC-02 contract from Chhatrapati Shivaji Terminal Station to Mumbai Central Station (Fig 1).

35

which are interchangeable with ripper tools, and feature large bucket openings that provide a 10% opening ratio.

The machines feature 2,000kW electric variable frequency drives that allow maximum cutterhead rotation of 7 rev/min and deliver a torque of 8,000kNm to cope with fractured rock zones. They have active shield articulation and built-in two component annular grouting systems.

The two re-manufactured 6.61m Terractec mixed/rock EPB machines deployed by the J Kumar–China Railway No 3 Engineering Group JV to fulfil a section of highly weathered ground on contract UGC-05, were used previously on the Delhi Metro and underwent extensive refurbishment.

When the 6.7m diameter Terratec TBM made its final breakthrough in 2019 for HCC/Moscow Metrostroy UGC02 became the first of seven contract packages to be completed. With production rates of up to 24m/day, the production record for the project, the machine completed its drives between NATM-excavated station boxes at Kalbadevi, Girgaon and Grant Road, on schedule and with negligible settlement, despite challenges that included proximity to the ocean, boring through reclaimed land, and congested working areas, as well as mining beneath some of the oldest buildings in Mumbai.

The first TBM to breakthrough on Line 3 was on the first 690m section of the UGC-06 contract from the CSIA International Airport Station to Sahar Road Station by one of three Terratec dual mode hard rock TBMs working for the J Kumar/China Railway No 3 Engineering Group JV. “The Terratec dual-mode TBM worked successfully through mixed geology and considerable water ingress,” said Haluk Emre, UGC-O6 Project Manager for the JV. Three Herrenknecht TBMs, one new and two refurbished EPBMs, completed the 10.43km of tunnelling for contract UGC-04 from Worli to Dharavi for the ITD-TATA-CEC JV. The three TBMs are completing the tunnels in four twin drives of from 600m from the Naya Negar open-cut launch site to Dharavi, to 2,490m, the longest drives on the project, between Naya Nagar and Dadar.

On UGC-07, the L&T-SUCG JV operated three STEC EPBMs, two refurbished and one new, to complete the 7km of twin tunnelling from Marol Naka to Seepz in the north. The three machines completed their tasks in three drives passing through MIDC and Seepz Stations to the transition ramp to the surface station at Aarey and the surface depot. The last

TBM completed its drive in December 2019 with contract UGC-07 being the first to complete all its TBM tunnelling.

Robbins applied technology

Through the hard basalt rock on UGC-01 from Cuffe Parade to Hutatma Chowk in the south, the L&T-STEC JV selected two XRE Crossover TBMs from Robbins. The two 6.65m diameter TBMs were required to work through mixed conditions of basalt rock with transition zones of shale, tuff, and breccia. The hybrid-type rock/soft ground single shield machines worked beneath a cover of 15m-20m with sensitive structures on the surface, including the Mittal Towers and the historic Bhikha Behram Well. All were instrumented to monitor vibrations, movements, and potential settlement.

As expected, significant amounts of groundwater at up to 300 litres/min and up to 2 bar pressure were encountered between Cuffe Parade and Vidhan Bhavan. A TBM with the ability to excavate effectively in continuously changing conditions was required.

Optimised for abrasive rock using a robust cutterhead mounted with disc cutters and a reinforced screw conveyor at the centerline, the hybrid XRE Crossover machines can operate in open, closed and semi-closed mode using features designed to advance in soft ground with water inflows. Dual ratio gearboxes adjust cutterhead speed and torque to the geological conditions encountered and the screw conveyors and their bulkhead gates and discharge gates control muck extraction from the excavation chamber.

Conditioning with foam and polymers and probe drills for pre-excavation grouting assist TBM operations.

The cutterhead design of the maachine was optimised for hard rock with six peripheral bidirectional muck buckets. In extreme soft and running ground conditions, the opening ratio of the cutterhead can be increased by removing part of the face plates and installing soft ground cutting tools.

The roll angle of the TBM is maintained by alternating the cutterhead rotation at each TBM stroke. This allows for a simpler thrust system, eliminating the need for a skew ring.

A screw conveyor in the centre of the XRE Crossover TBM offers several advantages over both traditional hard rock and EPBM designs. Full mucking of the cutterhead chamber in rock mode via six loading plates that continuously scoop and deposit excavated material from the invert into the screw conveyor inlet allows for minimal wear by keeping the amount of rocks inside the chamber to a minimum. The

Robbins Crossover TBM ready for dispatch to Mumbai; One of two Robbins/NFM rock slurry TBMs ready to start on UGC-03

36

centre screw also offers the ability to work in pressurised modes to control ground water, with the cutterhead chamber full of material and using the screw conveyor as a plug to maintain pressure at the excavation face. This is vital for avoiding ground settlement at the surface.

Extra wear protection was added to the screw conveyor and the conveyor included a replaceable casing liner, replaceable flight plates, and extra access doors in the casing for maintenance and replacement of the wear plates.

A major advantage of the centre screw Design of the Crossover XRE machines and peripheral muck buckets is a The cutterheads of the machines are fitted with wear substantial reduction in wear to cutter tools compared to an protection, wear detection bits, and Robbins 17in disc EPBM boring in rock. An average of almost 600m3 of rock cut/ cutters. Grizzly bars will limit the size of boulders entering cutter is an impressive statistic when assessing basic cutter the cutterhead to 250mm. The slurry systems include rock costs. From an operational point of view, 17 linear meters of crushers and abrasion-resistant plating in high-wear areas. boring/cutter reduced the frequency of interventions to an average 54m of boring.

“The Robbins presence in India, including field service crews, will be a great support for us,” said DV Raju, Senior The TBMs were equipped with a foam plant feeding six Vice President for Soma. injection nozzles on the cutterhead and one at the inlet of the screw conveyor. Foam controls dust in the excavation As excavation works approached their ends, attention for chamber in rock mode, reduces friction and wear in soft the project turned to finishing works and M&E installations. ground mode and reduces the permeability of the ground to All NATM stations, crossover caverns and cross passages reduce ground water inflow. are to be finished with a waterproofing membrane and reinforced cast concrete. Also ordered from Alstom are the A drill rig installed on the erector ring drilled through 12 ports 31 metro trainsets of 248 cars for the new line services, to around the TBM shield at a 7˚ angle from the TBM axis and be manufactured in India and supplied from the Alsthom through six ports straight forward through the cutterhead for factory in SriCity, Andhra Pradesh. probe holes and for pre-excavation grouting to consolidate and seal the ground in front of the cutterhead and permit higher boring rates. Several lubrication ports installed radially along the TBM shield inject bentonite to reduce friction in sticky conditions or squeezing ground.

While the term hybrid machine has been used in the industry for some time, Robbins claims the Crossover XRE TBMs are truly hybrid and able to change from rock mode to soft ground mode almost instantly.

On UGC-03 from Mumbai Central to Worli, the Dogus/ Soma JV is using two 6.65m diameter NFM/Robbins rock slurry TBMs, one new and one refurbished. The first TBM completed its 2,073m drive from Science Museum to Worli in 16 months, after launching in September 2018, being pulled through Acharya Atrey Chowk station box, and achieving final breakthrough in February 2020. The second 1,645m drives for the two TBMs, from Science Museum to the Mahalaxmi Metro open-cut station box and on to Mumbai Central, were on the critical path of the TBM excavation programme for Line 3 and completed their drives in November 2022 after launching in mid-2020.

The JV selected slurry machines for its contract due to the challenging ground conditions expected consisting of fresh to weathered basalt and breccia up to 100 MPa UCS with water pressures up to 3 bar. “I have worked with slurry TBMs in similar geology and the method will suit the hard rock geology of our Mumbai Metro contract,” said Tamay Sayin, Project Manager for the JV. “The water table and variable geology, especially basalt of higher strength, can be tackled by the Robbins slurry mode TBMs.”

“The schedule remains under continuous review and there have been some delays and challenges imposed by the coronavirus pandemic, and with the construction of the open-cut stations and structures very close to buildings,” reported Project Director Gupta. “However, we keep our target dates for opening Phases 1 and 2 of this important addition to metro services in Mumbai in sight.”

NATM station excavation

As well as many open cut stations, several of the Mumbai Line 3 underground stations were designed as NATM excavations or a combination of both, some introducing cutting edge development of waterproofing, shotcreting and excavation support systems.

For creating the Kalbadevi Station, located in the heart of the heritage district of Mumbai on contract UGC-02 by the HCC/Moscow Metrostroy JV, the design approach for focused primarily on minimising disturbances to the surroundings.

The geology for the area is mostly Class-II and I basalt with high compressive strength and few fractures. The approach adopted includes removal of the earlier TBM drive segmental linings followed by widening of the platform tunnels and construction of three 6.7m adits to connect the platform tunnels to the central concourse cavern using drill+blast excavation (Fig 2).

Approximately 1,200 segments in a total 304 x 1.4m wide rings of segmental lining had to be demolished to create 37

segments to release any built-up water pressure behind the lining and temporary u-channels and rockbolts supported the lining rings before removal and against the anticipated increased stresses of adit excavation.

Fig 2. Platform level plan of Kalbadevi Station and its excavation sequence

A small 2.8m x 3m transition zone breakout from the running tunnel gave way to the larger 6.7m x 7.5m adit excavation for subsequent breakout and enlargement of the station platform cavern and adit excavated to platform level.

The next phase in the sequence, to excavate the station platform tunnel and removal of the TBM lining segments to platform level, was the most challenging task. The sequence had to ensure stability of the rock in the crown and around the TBM tunnel as gradual enlargement progressed, excavating in the longitudinal direction (perpendicular to the existing TBM tunnel) and installing the primary support of rockbolts and shotcrete according to the rock Class (Fig 3).

Fig 3. Transition zones for platform enlargement excavations

the 211m long station platform tunnels. Two 27.5m deep cut-and-cover access boxes at each end of the station were constructed to base slab level using secant piles to support the excavation.

Within the 5.8m i.d. downline running tunnel, segments were marked for breakout of the three proposed concourse connection adits. Holes were drilled into the breakout NATM mined stations in highly congested areas

38

Excavation then progresses longitudinally to excavate the crown and platform tunnel and remove the TBM segmental lining to platform level and above a temporary invert backfill. The process is completed with drill+blast excavation and primary support of the bench and removal of the temporary backfill and invert segments of the segmental lining along the full 211.45m length of the station platform.

Station structures will be finished with a waterproofing membrane and a final in-situ concrete permanent lining to 9.5m wide x 8m high i.d. for the platform tunnels, to 6m wide x 6.5m high i.d. for the adits and to 9.5m wide x 7.6m high for the central concourse cavern. The twoaccess cut-and-cover shafts at either end of the station will become the ingress and egress structures and will also provide space for electrical, mechanical and ventilation systems. n

Kolkata Metro

M

ass rapid transit development for cities in India began in Kolkata in the 1970s. The early phases of construction included underground bored tunnel alignments between open-cut stations beneath the centre of the densely populated city.

With little to no experience of urban underground excavation, the authorities in Kolkata sought the assistance of experienced tunnellers from Hungary.

Gus Klados, who has worked on many large tunnelling projects in his career including the Channel Tunnel, deep drainage tunnels in Singapore, the SMART road and flood relief tunnel in Kuala Lumpur, the start of the Kuala Lumpur MRT and is now working on metro projects in Australia, was a young engineer from Budapest who joined the team of engineers from Hungary who travelled to Kolkata and he recalls the experiences of operating early tunnelling shields and in working in a compressed air environment to maintain control of the excavation face and protect surface structures from surface settlement.

The metro extension in Kolkata takes the service under the Hooghly River

While extensions to the initial operating system, only limited underground alignments was included, until approval for construction of the current extensions to the Green, Purple, Yellow and Orange Lines by the Kolkata Metro Rail Corporation. Of these, Afcons, in joint venture once again with Transtonnelstroy of Russia, is progressing its Rs 938 crore contract to take the metro system under the Hooghly River to connect Howrah Maidan station on the west bank to Central Station on the east.

This is the first under river crossing for any metro system in India and where it was anticipated that a slurry machine would be used to excavate the soft river soils, the JV has said it will use an EPB machine from Herrenknecht. The 3km long twin running tunnel section with its 520m section up to 30m below the river (15m below the river bed) and its three stations at Howrah Maidan, Howrah, and Mahakaran, is expected to take four years to complete.

Also in Kolkata, ITD Cementation Ltd, is awarded the eastern 4.5km section of twin tunnel underground alignment from Central Station to Phool Bagan. The JV is using two refurbished EPBMs that ITD procured from Herrenknecht for work on the Delhi Metro. n

Chennai Metro

I

n 2010, sixteen groups from different parts of the world prequified to bid the underground sections of the new metro system (Table 1).

Phase 1 of the project comprises two lines for a total 45km with more than half the length, 24km, aligned underground - 14.3km on Line 1 and 9.7km on Line 2. The underground works were packaged as five design-build contracts for open cut stations and their associated twin tube TBM running tunnels.

Construction of the metro was approved by the venteal Government of Tamil Nadu in November 2007 and by the Government of India in January 2009. The base cost of the project was estimated at about Rs.14,000 crores or nearly US$3 billion which is to be financed 41% by the Central and State Governments and the balance met by a loan granted by the Japan International Cooperation Agency (JICA) under an agreement signed in November 2008.

General Consultants to Chennai Metro Rail Limited (CMRL) for Phase 1 is a five-member consortium led by Egis Rail S.A. of France with Egis India Consulting Engineers; Maunsell Consultants Asia of Hong Kong; Balaji Rail Road Systems of India, and Yachiyo Engineering of Japan.

Appointed in February 2009, the General Consultants will assist CMRL in the design, supervision, quality control, safety and contract management for the project. The Delhi Metro Rail Corporation (DMRC) is appointed as Prime Consultant to CMRL to assist in an advisory role during execution of the project.

The five design-build contractors for the underground works were to be awarded before the end of 2010 and Phase 1 was to be completed and in operation during 2014-2015.

Of the five design-build packages, contracts UAA-01 and UAA-05 for a total value of 2598 crore INR (about US$577 million), was awarded to Afcons and its Russian partner Transtonnelstroy. The JV will use five TBMs to complete the total 8km of twin tube tunnelling. The GammonMosmetrostroy JV submitted the lowest proposals for contracts UAA-02 and UAA-03 for 6.4km of twin TBM running tunnels and seven underground stations. The two contracts are valued at a total 1,980.3 crore INR (about US$440 million). Gammon said it will construct the underground stations with its partner Mosmetrostory managing the running tunnels using four machines.

The fifth UAA-04 contract was awarded to the L&T-SUDG (Shanghai Underground Construction Group) on which it will use two STEC TBMs built in Shanghai. These were 39

Table 1. Prequalified applicants for five design-build underground station and associated tunnels contracts 1.

Bouygues Travaux Publics, France

2.

Sembawang Engineers & Constructors, Singapore

3.

Samsung-Soma JV, Korea/India

4.

Metrostroy-ERA JV, Russia/India

5.

Gammon –Moscow Metrostroy JV, India/Russia

6.

GYT-Coastal JV, India

7.

Alsim Alarko Sttas-NCCL-Gülermak Asitas JV, Turkey

8.

ITD-ITD CEM JV, Thailand/India

9.

Trandstonnelstroy-Afcons JV, Russia/India

10.

Lansen &Turbo-SUCG JV, India/China

11.

Strabag-Jaeger JV, Austria/Switzerland

12.

HCC-SELI-SB JV, India/Italy

13.

IVRCL-Kyiv Metro Bud (KMB) JV, India/Ukraine

14.

CEC - Continental Engineering Corporation, Taiwan

15.

Alpine Bau, Austria

16.

Doosan-Samwhan-CCCL JV, Korea/India

among the first Chinese made TBMs to be used on projects outside of China along with those used by SUDG in Singapore on its metro works.

Start of underground metro works in Chennai was not easy. Difficult ground conditions, a contractor walkout, the retendering of two of the five underground construction contracts midway through completion, plus devastating floods that hit the city in December 2015, combining to hinder overall progress.

The twin running tunnels of the system run through a mixed geology comprising soft ground and sand, through transitions with clay, weathered and fractured rock, hard granite, gneiss and boulders, all beneath a high groundwater table. This has challenged the 12 TBMs procured for the Phase 1 project.

From top: Changing the cutter discs on Chennai Metro (Picture by Jurgen Mick); One of many 28m deep TBM working shafts

Initial network of the Chennai Metro alignment across and beneath the city centre

After three years of hard-fought tunnelling, contractor Afcons overcame challenging conditions and high cutter wear to record the second and final breakthrough for its Robbins EPB on Contract UAA-01 in January 2016. The TBM completed a section below the Koovam River without any water ingress and achieved a best daily advance rate of 12.6m, and a best weekly figure of 62m.

Breakthrough into the reception shaft at Central Station by the Robbins EPBM in early 2016 left four of 17 TBM drives to finish. In total, 12 EPBMs have been involved in construction of the total 36km of running tunnels for the underground sections of the Phase I network.

The underground works was thrown into disarray in May 2015 when contractor Metrostroy walked off Contract UAA02 and away from its joint venture with Gammon on UAA-03.

The Russian contractor left behind construction equipment and materials valued at several million dollars, including all four Herrenknecht TBMs procured for both contracts after failing to reach agreement with CMRL over escalating costs.

After cancelling contract UAA-03, and calling in the contractor’s bank guarantee of approximately US$15 million, CMRL awarded the balance of tunnelling works to Afcons, which had completed the running tunnels of Contract UAA-05 in JV with Transtonnelstroy of Russia.

Robbins breakthrough in Chennai

40

The balance of construction on Contract UAA-03 was taken over by L&T after completing Contract UAA-04 in JV with Shanghai Urban Construction Corporation (SUCG). Interest in taking over the half-finished UAA02 Contract as BW-UG-02, has been expressed by L&T and Afcons, as well as by HCC and Coastal. The severe flooding that brought chaos to Chennai in December 2015 inundated the incomplete running tunnels and the new

Lucknow Metro

C

onstruction of the metro in Lucknow, the capital city of the most populated state in India, Uttar Pradesh, began in 2016. Aiming to bring worldclass infrastructure to the city, Phase 1 of the two-line metro system had an estimated cost of 6,928 crore INR (about US$1 billion), with construction of Phase 2 due to start in 2018.

For construction of the Phase 1A north-south line, the Tata/Gülermak construction JV took delivery of the two 6.52m diameter Terratec EPBMs, the first TBMs to be used in the city. The TBMs excavated twin 1,812m long running tunnels from a ramp portal to the underground alignment near Charbagh Metro Station to the opposite surface transition ramp near KD Singh Babu Stadium Metro station (Fig 1).

The 36-month EPC - engineering, procurement, construction - contract awarded to Tata-Gülermak JV in April 2016, included construction of three open cut stations at Hussainganj, State Secretariat (Sachivalaya) and Hazratganj.

The machines will be delivered to the Sachivalaya station site in mid-November and early December 2016 and launched for the first 780m drives towards Hazratganj.

They will work through geology consisting of stiff to hard clayey silt and medium to dense silty sand and under an average overburden of 4m to 10m. The drives are lined with rings of 275mm thick x 1,400mm long, reinforced concrete universal-style, precast concrete segments, comprising five segments and a key in each ring. The segments were manufactured at a local casting yard in Vrindavan.

contractor will have to repair both UAA-02 TBMs. One was already damaged and both will require all their electrical components to be repaired or replaced.

The above four construction companies have also expressed interest in bidding for the new underground extension Contract UAA-08, along with Tata, Solentache Bachy, SUCG and Soma. n In 2017, breakthrough of the Terratec machines after completing their first 812m long twin tunnels was celebrated by the tunneling crews and managers of the Gülermak-TATA JV together with representatives of Terratec, and senior officials from the Lucknow Metro Rail Corporation (LMRC). The two EPBMs took four months to complete the first 812m long drives.

Speaking at the ceremony, LMRC Managing Director Kumar Keshav said; “the tunnelling in this stretch posed several technical challenges as the route passes beneath highly congested areas and beneath historic buildings in the Capital Plaza heritage district of Hazratganj. This breakthrough represents a milestone for our project.”

With tunneling work completed between Sachivalaya and Hazratganj stations, the TBMs were reassembled back at the western-end of Sachivalaya Station to excavate the twin 613m tunnels towards Hussainganj Station.

From there, they will continue a further 419m crossing underneath the Haide Nalah canal, to breakthrough at the cut-and-cover transition ramp to the surface alignment near Charbagh station (Fig 1).

The east-west Phase 2 line involves a longer length of twin running tunnels from Charbagh to near Thakurganj with six Gulermak-TATA Projects JV celebrate Lucknow Metro breakthrough

The EPB machines featured a classic spoke-style soil configuration cutterhead with a 57% opening ratio. Terratec designed the cutterheads for interchangeable cutting tools, using either drag teeth or 17in disc cutters, allowing the TBMs to bore through station box diaphragm walls and cope with the presence of any unexpected obstacles.

From left and Fig 1. The two Terratec machines used in the city on the underground section of Lucknow Metro Phase 1A

41

intermediate underground stations. Phase 2 of the system is due to commence in 2018.

When the two 6.52m diameter Terratec EPB machines broke through simultaneously at Hussainganj underground station in 2018, they marked completion

of tunnelling works on the 3.67km long CharbaghHazratganj section in about 15 months. The final drives from Charbagh to Hussainganj were particularly challenging, passing 1m below the bed of the Haider Nallah canal in a highly populated area full of dilapidated structures on weak foundations. n

Pune Metro

F

ollowing successful factory acceptance tests in 2019, the first two of three Terratec 6.6m EPBMs were delivered to the Gülermak-Tata Projects JV for its underground works contracts on Line 1 of the Pune Metro in Maharashtra State. This follows a major funding milestone for the project signed off by the European Investment Bank. Consultancy services to the client for Line 1 are provided by Systra, AECOM, EGIS and RITES. Early in 2019, Maharashtra Metro Rail Corporation (MahaMetro) announced that the joint venture had won both packages of the twin-tube underground alignment of the new 16.6km north-south metro corridor. The 5km underground section with five underground stations that runs from the College of Agriculture in Shivajinagar to Swargate, is considered the most challenging portion of the line, as it passes under the densely populated areas of Kasba Peth, Budhwar Peth and Mandai market (Fig 1). The two other TBMs for the project were being manufactured at the Terratec assembly plant in Nansha district, Guangzhou, in Guangdong province, China.

Along with the twin-tube EPBM drives, the Gülermak-Tata JV includes design and construction of the Shivajinagar and Civil Court underground stations on contract UGC-01 and the Budhwar Peth, Mandai and Swargate underground stations on UGC-02 (Fig 1). Contract award value of UGC-01 is a combination of USD$124.2 million in INR plus USD$37.6 million, and for UGC-02 is USD$119 million in INR plus USD$40.57 million.

Fig 1. Pune Metro Line 1 includes a 5km underground section

1.4m wide x 275mm thick rings of precast concrete lining, consisting of five segments plus a key in each ring.

In 2020, after achieving a best monthly progress of 301m, the JV celebrated a TBM breakthrough into the northern end of a 155m NATM crossover at the start of the Civil Court Station.

Pune is an industrial city that has witnessed much growth in the areas of corporate and industrial infrastructure over the Pune Metro breakthrough into the NATM crossover cavern

“We are ready to launch the first two Terratec TBMs,” said Ashish Dwivedi, Geotechnical Manager for the Gulermak-Tata Projects JV. “Terratec TBMs have a good track record in India and we expect to complete our 5km Pune Metro Line 1 twin tube excavation within the project schedule.” Major challenges on the project will include passing beneath old structures, under the River Mutha and launching and retrieving TBMs with limited access in the built up areas near Budhwarpeth and Mandai Stations.

The Terratec EPBMs have mixed-face dome-style cutterheads designed to work effectively in the compact basalt expected on the alignments. As the TBMs progress, they will operate at pressures of up to 4 bar and install From left: Terratec TBMs successfully factory tested; Design of Swargate multimodal station hub

42

last decades. Existing roads in the city currently carry an average of 8,000 commuters an hour in each direction and the city experiences hours of traffic jams during peak hours that leads to increased pollution. The Pune Metro aims to provide a solution to the issues by offering a safe and ecofriendly journey with a 50% reduction in travel time.

With two lines in development, the project is constructing

a total 31.3km network with 30 stations. The budget for the complete project is almost €1.8 billion (USD$1.9 billion) with a European Investment Bank loan of €600 million (USD$657 million) and additional funding of €245 million (USD$268 million) by the French Development Agency.

In operation, the Pune Metro network will comprise three rail corridors with a total length of 54.5km. n

Agra Metro

O

ne of the most recent cities in India to start development of a metro system is Agra, the site of the famous Taj Mahal about 230km southeast of New Delhi. Phase I of the project comprises two lines with 28 stations for a total of 30km. Construction of the AGCC-02 7.5km underground section of Line 1 with six underground stations between the RBS College transition ramp in the north and the Taj Mahal transition ramp in the south was awarded to the Afcons-Sam India JV in early 2022 for a bid value of 1,819.79 crore and a contract period of 48 month.

UPMRC, Uttar Pradesh Metro Rail Corporation, as the client, and its General Consultant TYPSA-Italferr JV required that four TBMs be deployed to complete the twin running tunnels. Two of these four machines, and the first on-site and into their drives, are two 6.65m diameter soft ground spoke-type cutterhead Robbins TBMs. In April 2023 the first Robbins machine made an intermediate breakthrough into the station box to complete the Jama Masjid to Agra Fort stretch of the alignment. After launch

Two Robbins soft ground TBMs with spoke-type cutterheads are the first on site for the Afcons-Sam India JV

Phase 1 of the Agra Metro incorporates a 7.5km underground section of twin running tunnels and six underground stations on Line 1

in February 2023, the machine bored a total of 345m in sand and clay and will continue to complete it total drive of about 3km, its twin TBM launching in April 2023 to complete the parallel running tunnel.

In early April 2023, the JV also took delivery of a refurbished 6.63m diameter EPBM from Herrenknecht as the third of the needed four TBMs, following a successful factory acceptance test at the Herrenknecht factory in Chennai. The TBM launched in August 2023. With three TBMs in operation the JV is boring metres and drawing down its stockpile of precast concrete segments.

Meanwhile, start of train operation testing on the priority route of the 3km long elevated section of Phase I Line 1 is progressing toward inauguration of public services on the priority section that includes a 2km section of the underground route of the line from Taj East Gate Metro Station to Jama Masjid Metro Station by February 2024 six months ahead of scheduled date in August 2024.

Construction of the Phase I network will then continue to bring metro transit services to the population and visitors to the famous tourist destination. n

From left: In April 2023 a Robbins TBM achieved the first TBM breakthrough for the project A Herrenknecht EPBM is the third of the four TBMs needed on the AGCC-02 underground works

43

Regional commuter rail networks NOVEMBER 2023

A

Shani Wallis, TunnelTalk

new phase of rail infrastructure construction in India is a programme of creating semi-high-speed links with limited station stops between major city centres and regional satellite towns and cities. The objective of the programme is to reduce dependence of commuters on road-based transportation into city centres and to take advantage of less expensive residential housing and more living space and amenities in satellite towns and suburbs compared to major city real estate property prices and dense urban environments.

The first programme of Regional Rapid Transit Systems (RRTS) is being developed by the National Capital Region Transport Corporation (NCRTC) for the capital city Delhi where eight radial lines are planned, all of them terminating at the central Sarai Kale Khan RRTS station (Fig 1). From here commuters will join the Delhi Metro system for onward journeys to offices and work locations within the city. Of the eight planned links, three have been prioritised for start of construction. All three Lines comprise long lengths of elevated infrastructure with sections in underground routes beneath congested city and town centres.

Work started first in 2019 on Line 1 between Delhi and the satellite towns of Ghaziabad and Meerut. Of the 82km link, 12km is aligned underground in two sections of twin running tunnels linking four underground stations using seven TBMs. For Package 4 at the Delhi end of the line, STEC, Shanghai Tunnel Engineering Co, deployed four 7.5m diameter STEC EPBMs on the 5.6km section in eight drives from the New Ashok Nagar transition ramp to the Sahibabad transition ramp with one underground station at the town of Anand Vihar. On Package 8 under the city of Meerut, Afcons used three 7.56m diameter Terratec TBMs to complete 4km of parallel running tunnels in six drives between the Brahampuri and Begumpul transition ramps and linking three open-cut stations.

Network of eight new commuter rail links planned for the Delhi capital city region

Earlier in 2023, TunnelTalk made a site visit to the Afcons jobsite arranged and hosted, with thanks, by Terratec.

At the site we met with Smark Klawkla, Tunnel Manager for Afcons who conducted the visit underground and provided details of the project and its progress.

“The ground here is fine dry sand that was once part of a riverbed,” explained Klawkla. “The watertable is very low, there is no groundwater at tunnel horizon, and there is no clay or hard bedrock in the geological profile of the alignment that runs about 15-20m below the surface.”

From left: Clear walkways on the Terratec TBM backup; Core of the Terratec TBM circled by its eight cutterhead drive motors; Looking back over the screw conveyor and transfer conveyor to the muck skips; Screw conveyor muck discharge

44

From left: Three Terratec 7.56m diameter EPBMs worked on the Meerut underground section; TBM working access through one of the underground stations; Anil Shukla of Terratec and Smark Klawkla of Afcons hosting tour of the works

To cope with these conditions, with very little stand-up time afforded by the fine dry sand, and a high risk of face collapses, Afcons and Terratec recommended EPB rather than a more expected slurry method for excavation. “With only 10m or so of cover, both heave and surface settlement were significant concerns with the potential for slurry pressure blowout to the surface,” said Klawkla. “With the use of foam, we are able to modify the sand to a medium that is more suitable to EPB excavation. To achieve this though, we are using a lot of foam and losing quite a lot in the fine sand.”

The foam, supplied by MBC (previously BASF), helped reduce cutterhead torque and create the necessary plug in the screw conveyor to keep the plenum full, control muck extrusion, and maintain the balancing pressure.

When TunnelTalk visited the site more than 72% of the tunnel excavation was complete and there had been no trigger-level incidents of either heave or settlement.

The 7.56m diameter Terratec TBMs, two completing drives of about 1.2km each and the third completing both shorter drives, have dome cutterheads to help support the sand faces, and a quite closed opening ratio of 37%.

The machines have eight cutterhead motors to deliver a speed of 1.7 rev/min and a torque of 5,700Nm on average and up to 7,000Nm when needed. Bentonite injected into the annual space prevents the dry sand collapsing onto the TBM shields. Advance in the sandy strata, excavated

by soft ground cutterhead tools, was up to 4-5mm/rev to excavate about 70m3/hr. Station excavation within diaphragm wall supports using excavators was also at about 65-70m3/hr. Mucking out was with loco and skips with five skips, two segment cars, a flat car and a grout car in each supply train. As the TBMs progressed, the 19 thrust rams pushed off rings of segmental lining comprising six segments and a key in each ring.

Afcons was the first to complete all tunnelling on its underground section, recording the last of six TBM breakthroughs in July 2023. In August 2023, STEC achieved its last of eight breakthroughs to complete all TBM excavation on the project. Final excavation on both contracts is construction of the cross-passages. On the Afcons project the cross-passages are about 15m-16m long and about 4.2m diameter. Excavation of the sandy soil by small backhoe machine is presupported by 500mm diameter forepoling.

With excavation of cross-passages advancing well, the expectation by NCRTC is to have the full 82km DelhiGhaziabad-Meerut link opened by 2025. Ahead of this, in October 2023, Prime Minister Modi inaugurated public services on a 17km long elevated section of the line. When fully opened, and with trains running at up to 160km/hr, the 82km trip between Meerut and Delhi will take about an hour. n

From left: Thrust rams against the segmental lining; Operators cabin; Afcons generated its own power for the jobsite and TBM operations; Muck bin for the foam conditioned sand ahead of onward disposal

45

CONFERENCE AND TRADE SHOW REPORTING: Major industry events in India have revealed much

about current, planned and aspiring infrastructure projects for the country. From hosting the WTC World Tunnel Congress and General Assembly of the International Tunnelling and Underground Space Association in 2008, to providing the venues for the bC bauma CONEXPO construction equipment exhibitions, most recently in Delhi in February 2023, India clients have played an important role in promoting the wider use of underground space in nation building. As an active Member Nation of the ITA, India is rising to its immense economic and geopolitical potential and is continuing to develop rapidly as an important market for underground infrastructure construction.

Nation building in India

FEBRUARY 2023

I

Shani Wallis, TunnelTalk

n his opening address at the bauma CONEXPO construction equipment trade show in February 2023, Shri Nitin Gadkari, Minister of Road Transport & Highways, reiterated the aspiration of the national Government of Prime Minister Narendra Modi (in Government since May 2014), of India becoming a 5 lakh crore INR (about US$5 trillion) economy by 2025. This is up from its current GDP of about 3.18 lakh crore, or about $3 trillion in 2021, and the prospect is in reach by all accounts, with India’s growth rate outpacing leading countries of the world in the coming years at 6-7% year, significantly higher than USA, China, the European Union and Japan (Fig 1 and Table 1).

Where agriculture, mining and steel production have been traditional areas of economic activity, and IT, pharmaceuticals and aerospace are the newcomers, the current Government sees national infrastructure expansion as the key driver of growth in the coming years. As Minister Gadkari said: “India is the third largest construction equipment market in the world presently” after the USA and China, and recently overtaking Japan.

“Making us number one in the world is my challenge to you construction companies and construction equipment suppliers. My next challenge to you is to make these units of equipment in India – including the components – and to become an exporter of these made in India machines.”

Export is where India has recognised potential, to raise its meagre 1-2% of current global trade.

For these nation-building aspirations, growth in the construction industry is a given. There are three mega cities of more than 10 million in India – Mumbai, Delhi, Kolkata – and 46 cities of more than 1 million population.

The need for airports, metros, roads, highways, railways, water, sewage, wastewater and stormwater management, and power generation is tremendous. Building these Fig 1. Projected growth for India in GDP to 2027 © Statista 2023

46

facilities over the coming years will take all of the central Government’s promised increase in capital expenditure on infrastructure investment in 2023-24 to about 3.3% of current GDP and almost three times the outlay in 2019-20. As the World Bank predicts, India will need an estimated capital investment of US$840 billion in urban infrastructure and municipal services in the next 15 years till 2036, or an average of $55 billion/annum if it is to meet the needs of its fast-growing urban population. For those who have visited India, the need is absolutely evident.

Using construction equipment sales as a measure of infrastructure development, India has maintained the same level of about 180,000 units sold/year since 2017. This is projected to grow by 5% in the coming years, better than several other countries of the developing world (Fig 2). In his speech, Minister Gadkari listed projects in India tasked with converting construction equipment from diesel to greener alternatives including LNG, electric power, ethanol, and hydrogen fuel made from biomass. “Make this transition for yourselves,” he warned the equipment manufacturers, “or we will impose a 50% increase on GST tax on making diesel vehicles”. He warned also of the construction industry’s need to “reduce air, water and sound pollution” and to “reduce the cost of construction by improving productivity and without lowering quality.

Big challenges,” he said, “but not impossible.”

India’s 1.3 billion-plus population, now the country with the largest population in the world, is both a driver in the urgent need for massive investment in national infrastructure and also an asset for its realisation. India has one of the world’s largest bodies of young, talented, well-educated aspiring professionals, one of the world’s largest diasporas of Indian nationals being educated and working abroad with the potential to return home, and one of the world’s largest and youngest work forces. Construction is one of the most important entry level opportunities into the economy for the unskilled and as Minister Gadkari said: “We must train them Table 1. Top ranking GPD countries in 2022 as compiled and reported by the World Bank Rank

Country

GDP (billions, USD)

1

United States

$25,035.2

2

China

$18,321.2

3

Japan

$4,300.6

4

Germany

$4,031.1

5

India

$3,468.6

6

United Kingdom

$3,198.5

7

France

$2,778.1

8

Canada

$2,200.4

9

Russia

$2,133.1

10

Italy

$1,997.0

Total World GDP

$101,559.3

and put the labour force to good use. We need them and we have a duty to them to train them for safe construction work.” Safety regulations, workers compensation for injuries, family insurance plans for construction worker fatalities, and occupational health standards and regulations, are all areas of construction labour force welfare that require Government and industry attention.

Doing business at the bC India show

Among the exhibitors at bC India, there were major suppliers to the Indian tunnelling industry and represented by their agents, including Palmieri, Normet, Häny, Schauenburg ventilation systems, and others, as well as four of the principal TBM manufacturers Terratec, CRCHI, Robbins and Herrenknecht. While visiting the TBM suppliers, it became clear that more than 100 TBMs of the 3m+ Fig 2. Global construction equipment sales in 2022 as reported by the VDMA diameter range will be needed over the coming two years and more than 50 of these will be working Disappointingly for underground advocates, is the sight simultaneously during 2023-2024. TBMs of large diameter of new highways and metro lines being built across cities are also being applied to new road and rail projects, a sector on less-expensive and faster-finished elevated structures, of infrastructure development that is expanding rapidly something that India may come to regret. On the other hand, (Table 2). There are 110 road tunnels with a total length of a fact that is becoming apparent is that urban density and 195km operating in India with many more in construction and the rising cost of urban real estate is increasingly forcing planned. The first TBM road tunnel in India is the Mumbai metro and urban road and rail planning underground. coastal road Phase 1 project, excavated by a 12.2m diameter TBM from CRCHI of China. As a relative new coming to the For India’s infrastructure growth aspirations, international TBM market, India is the largest market for there are some serious drawbacks including the CRCHI outside of China. The Mumbai road tunnel TBM was number of infrastructure projects that are delayed. its first order to India and it has 14 more on metro projects in According to the Ministry of Statistics and Programme India with more on order.

Implementation, of 1,438 current infrastructure projects in December 2022, 343 of them were running over While visiting the Rocscience stand, Consultant Dr Manoj cost by a combined total of some 4.5 lakh crore (about Verman explained that of the 125km length of the new US$5.5 trillion) and as many as 835 were delayed by railway line between Richikesh and Karnaprayag, 105km an average 40 months - 160 by 1-12 months; more than will be in tunnel. Herrenknecht recently delivered of the 400 by 25-60 months and 130 by more than 61 months. first of two 9m diameter TBMs for customer L&T from the The anticipated completion cost is estimated at an factory in Germany for the 10km long twin tube tunnel of overall overrun of about 22.12% of the original budgets.

Package 4 of the line.

The central Government is said to have established a budget specifically for funding delayed projects, but On the stand of a supplier of drill+blast consumables, the fear is that the revised cost and estimate of time to Vishal Agarwal, the comment was there was little impact completion has been under-reported. of TBMs on the drill+blast market. And to be fair, for the Strong funding commitments are required to provide TBM projects listed in Table 2, there are a factor of 10 construction companies was the confidence to take on times or more, the number of drill+blast projects underway large contracts, but funding cannot be from the public and in the pipeline. TBMs though are coming to compete purse alone. Private financing will have to be harnessed with drill+blast in a greater way on roads, railways, and to meet India’s infrastructure ambitions. There must also hydropower projects.

Table 2. As well as current TBM projects in India, several more are planned Project Purpose Contractor Number of TBMs and procurement status Pakal Dul Hydro - 2 x 7.7km L&T 2 x 8.3m double shields - Herrenknecht - on site RVNL Railway - 2 x 10km L&T 2 x 9m single shields - Herrenknecht - on site Mumbai-Surat Bullet Train In tender stage 3 x 13.2m diameter Afcons/SAM (India) JV 2 x Herrenknecht Kanpur Metro Gülermak (Turkey)/SAM JV 2 x Terratec Kanpur Metro In tender stage 2 required Kumar 2 x Terratec Surat Metro Gülermak (Turkey)/SAM JV 2 x Terratec Patna Metro L&T 2 - CRCHI, delivered, 2 more perhaps needed - TBC Mumbai Coastal Road extension In tender stage 1 x 12.1m machine required Thane-Borivali Road - 10km twin tube In tender stage 4 x 11.2m diameter Delhi-Shivmurti Road - 4km twin tube In tender stage 1 x 15.1m diameter GMLR Mumbai link road In tender stage 2 x 14.2m diameter MCGM Mumbai Water supply Soma Patel 2 x 3.2m diameter - Terratec CDCO Mumbai Water supply In tender stage 4 x 3.2m diameter

TunnelTalk Editor, Shani Wallis, attended bC India in 2011, 2016, 2018 and 2023

be renewed efforts for avoiding and arriving at timely resolution of disputes. Anyone with experience of the legal system in India will know that it is overwhelmed and moves very slowly. Another hardly spoken of drawback is the omnipresent practice of corruption. India ranks 85 of 180 countries on the current Transparency International Corruption Perceptions Index (CPI) and there was applause when Minister Gadkari said in his presentation that “corruption must reduce”. More must be done to outlaw this scourge, in India and everywhere in the world.

But for the moment, Prime Minister Modi and his ruling BJP party is asking the nation to believe that India’s destiny is now in its own hands. It is that self-belief that is fundamental to nation building.

Still however, India took time to appreciate its potential and how to maximize the advantage or manage the reality. The country in 2011 was still yet to start its leap forward that had been long predicted and anticipated.

India a reluctant powerhouse

At the bC India exhibition in 2016, comments included that bureaucratic red tape continues to hold back initiatives, plans for new projects take years to move into construction, incompetence or poor management of issues on projects delay their finish until long beyond the programmed service date, projects always seem to be half finished in the final details, and the urgency to keep the projects rolling from one phase to the next seems missing.

The inaugural bC bauma CONEXPO Show was in February 2011 where organisers, Germany’s Messe München International (MMI) and the Association of Equipment Manufacturers (AEM) of the United States, who run the bauma Munich and ConExpo/ConAGG Las Vegas monster events respectively, explained: “There is a need for fewer exhibitions that are run better, and as a joint venture with IMM, we are looking to develop leading shows in other parts of the world.”

Similar to the great economic surge that China experienced in the early 2000s, could India experience, implement or manage such a similar economic surge was the question. In a conference presentation, a comparison was made that, at peak, the number of truck mounted concrete pumps in China in 2010, totalled some 12,500 units/year. At peak in India in 2011, the number of the same truck mounted concrete pumps in India was 150 units.

The number of these units into Turkey at the same time was more than 500 units/year. But as everyone agreed, “We should not be pessimistic, but we should also not be too optimistic. We should be realistic.”

The first bC India event followed selection of India as the partner country for the bauma Munich event in Germany in 2010. In his keynote address at the event, Kamal Nath, the Minister for Road Transport and Highways in 2010 explained: “Given our historical underinvestment in highway infrastructure, we believe it is imperative that adequate investment is attracted to this segment. To achieve this, the biggest challenge is to bring about an attitudinal change of the people involved. For one, we must believe that we can build 20km a day. We have also changed many of the provisions that were seen as increasing the risk of PPP procurement of highway projects and now have a level playing field for the Indian and foreign companies and the projects are bid out on international competitive bidding.”

By bC India 2018, prospects for the construction industry had remained much the same although a sense of capacity had set in - capacity of funding, capacity of construction and engineering resources, capacity of skilled labourers, capacity for project planning. Prospects for the underground construction equipment industry only for a year later, in late 2019/early 2020, the world to be plunged into the surreal shutdown in efforts to control the spread and impact of the Covid 19 pandemic. After cancellations of the events for four years, the return of bC India in February 2023 in Noida, Delhi presented something of a new dawn for the construction industry with the tunnelling industry set to benefit by this as cities across India plan and push forward with road, rail, water management and metro system projects.

bC India shows impress

Hosting the World Tunnel Congress and ITA in 2008

O

ne of the most significant events in the underground construction industry for India was its hosting in 2008 of the World Tunnel Congress and the General Assembly of the ITA International Tunnelling and Underground Space Association in the famous city of Agra near Delhi. More than 800 delegates attended the event, more than 65 papers were presented and more than 65 national and international companies had booths in the inside exhibition hall and outside in the gardens of the hotel venue.

48

Minster of Hydropower and Energy, Sushil Shinde, gave the opening address and set the proceedings on an

interesting exploration of tunnelling projects and practices both in India and abroad. Of particularly focus was the current and future development of the vast wealth of hydropower for India that exists in the mighty Himalayas and the experiences to date of harnessing that energy technically and contractually.

Among the highlights of the program was the ITA Open Session that discussed contractual practices worldwide.

The opening paper by J.M. Barros and Andre Assis, discussed An Independent View of the Pinheiros Station Accident on the Sao Paulo Metro and Lessons Learned.

By way of recommendations, the paper suggested that

design-build contracts need to give more responsibilty to the designer, more strength to the process of quality control, and “by no means” employ the process of self-certification.

Contract Models in Underground Construction Experiences from an Owner Viewpoint was the presentation of Heinz Ehrbar and was based on his experiences as Chief Construction Manager of the Alp Transit Gotthard Ltd company in procuring the twin 57km long rail tunnels through the base of the massif. Ehrbar started by comparing current contractual practice with those employed for construction more than 100 years ago of the existing Simplon and Old Gotthard rail tunnel under which all ground risk was with the contractor. “This was a disaster for the contractor who had to pay heavy late delivery penalties” and went broke as a result of the effort. From his own experience as an owner, Ehrbar agreed, “the ground belongs to the Owner but the means and methods belong to the Contractor” wherein lies great room for dispute and gray areas of interpretation.

He also recommended a unit-price based contract as the most economical and fair method of procurement for both parties; a DRB as the first vehicle for assessing and settling any disputes; and the establishment of national codes to suit the construction norms and legal systems in each country.

TunnelTalk Editor Shani Wallis (right) speaks with ITA President Martin Knights (left) and Minster of Hydropower and Energy Sushil Kumar Shinde at WTC2008 in Agra

to the advantage of the Owner but in that case the Contractor doesn’t lose, he just doesn’t get paid for what he doesn’t do. Simple.”

• for a DRB - “providing it is permitted to function properly”; and • for “contracts to be written to be understood by engineers - and not for lawyers.”

This last point raised spontaneous applause in the audience.

In his presentation, Contractual Practices Worldwide - Engineering Sector Views, Yannn Leblais of Arcadis, France started by stating that insurance claims for failures in tunnelling over recent years lay more than 50% of the cause or blame with the design and the geological investigation of the project. Because of this he called on all sectors of the industry to pay more attention to design. In criticizing the actions of some owners and fellow designers, he said the designers need to be “in the ground” with the contractor and not in remote offices trying to control design from a distance. He warned fellow designers not to become “intellectual slaves” to contractors in design-build projects and questioned the ultimate responsibility in PPP projects asking “who has the right to stop the ongoing work on the site” under these increasingly popular procurement vehicles.

Tailoring New Contractual Frameworks for the Demands of the Local Market was the topic of Arnold Dix from Australia, who aurgued that while each country is free to prepare contractual practice according to local legal and operational systems, they must base these on best practice as already established in other countries, particularly if the intent is to attract interest from foreign contractors and consultants.

Christian Genschel of Bilfinger Berger of Germany presented a take on the Contractor’s Views and Wishes.

Genschel called on several actual experiences to make his case: • for being given sufficient time to prepare bids - “a call to prepare a bid within three weeks resulted in bids all two times the estimate”; • that Contractors are not gamblers - “the Owner has to know what he wants in specific detail and we have to bid against a firm scope of works”; • for unit-price contracting - “unit prices can also be

Missed opportunity

To round out the session, H K Sharma, Chairman and Managing Director of Satluj Jal Vidyut Nigam Ltd of India and D G Kadkade, Chief Advisor to Japiprakash Associates Ltd of India presented two papers on the Contractual Practices in Tunnel and Underground Works in India, which highlighted just how particular India’s practices are compared to other international systems.

Those who decided not to attend the Congress in Agra, missed a chance of a lifetime to visit the home of the famous, and truly remarkable, Taj Mahal, (unless they had visited the city before); missed the hospitality and effective administration of the organizers; missed an introduction to the vast amount of tunnelling needed through out the country to increase its economic wealth and raise the standard of living for so many of its 1 billion-plus population; and missed a most enjoyable gathering of the ITA ‘family’ until the 2009 event in Budapest, Hungary. n

49

High altitude location of the project taxed construction phase men and machinery

Rohtang pushed NATM to the limits

CASE STUDY: The majestic Himalayas and their foothills in northern India, as well as in the

mountain kingdoms of Nepal and Bhutan, present a formidable barrier to infrastructure excavation for roads, railways, water, and hydro schemes. The high altitudes, extremes in climate and remoteness, inaccessibility, tremendous overburdens and a young geological formation that is constantly under stress and seismic activity are all contributors to making man’s efforts to tunnel through the Himalayas an undertaking of courage, risk, skill, expertise and determination. The Rohtang highway tunnel between the States of Himachal Pradesh and Jammu and Kashmir is just one example of many where success came at a cost but did eventual come.

NOVEMBER 2020

E

Roland Herr for TunnelTalk

xtreme working conditions at an altitude of more than 3,000m above sea level, water ingress of more than 250 litre/sec, high rock pressures with extreme deformations and rapid changes in geological conditions presented major challenges during excavation of the Rohtang road tunnel in the Himalayas in India. Contractor Strabag, in joint venture with Afcons, explained how conditions pushed the NATM excavation method and the crews to the limit during the 10-year construction period from 2009 to 2020.

The 8.9km long, single-tube tunnel was constructed under a contract of about €250 million to avoid the dangerous route over the Rohtang Pass, shorten the Manali-Leh Highway by about 50km, and provide an all-season route between Himachal Pradesh State and the State of Jammu and Kashmir. The 13m wide excavation accommodates two traffic lanes, two footpaths and an emergency egress beneath the carriageways with entry points every 500m.

The 50cm thick unreinforced in-situ final lining was designed with no systematic waterproofing system and

an intermediate ceiling provides for transverse ventilation and smoke control (Fig 1).

The high altitude and its rare atmosphere affected personal health as well as a loss of equipment performance.

Excavation was planned to progress using drill+blast from both portals however getting to the job site was a challenge with load restrictions on bridges and landslides, falling rocks and extreme weather conditions a regular occurrence on the local roads. Under these conditions, construction work at the north portal was only possible for about six months each year.

Drill+blast excavation started in 2010 and progressed on a top-heading, bench and invert sequence on a cross section that ranged from 140m2 to 205m2 depending on the excavation class.

With the rock formations unsuitable for determining designed excavation classes, a change to the NATM processes was incorporated into the design and ground behaviour was stipulated as an additional criterion. This meant that monitoring was an essential part of the NATM excavation process.

Largest influx of material (left) and chain reaction collapse towards the face (centre); Fig 1. Design of the two-lane road link (right)

50

At about 1.93km into one of the portal headings, horizontal deformations combined with severe cracking of the shotcrete primary support resulted in failure of the heading.

Water ingress increased, with up to 150 litre/sec inflow recorded from the top-heading face alone.

At 2.05km into one of the headings a major collapse occurred causing an inflow of about 400m3 of watersaturated material. Several further collapses occurred as the drive progressed. The largest inflow of loose saturated material was about 1,000m3. The high level of water ingress created cavities primarily in the crown area. At 2.4km the pipe umbrella pre-support collapsed with deformations in excess of 800mm recorded in the crown. The area was recovered with timbers and shotcrete. The conditions were subsequently linked directly to a watercourse on the surface.

As the heading approached the main identified fault zone, new excavation classes were defined to increase the support resistance. Additional anchors were installed and drainage pipes were inserted to manage water ingress. Pipe umbrella pre-support was installed on 15m rounds at the start of the main fault zone. As geotechnical and geological conditions deteriorated, the pre-support pipes were lengthened, the pipe diameter was increased from 76mm to 114mm, the pipe rows were doubled and the spacing reduced to skin-to-skin with internal reinforcement added.

Excavation of the 44km long AMR water conveyance project in India is an awesome undertaking. Know of the optimism at the start, the setbacks and struggles to date, and the renewed determination to get the project completed and into service

Direct by Design

AMR water supply drive

An epic tale of long distance TBM excavation

Underground in Action U

After various trials, the top-heading was eventually advanced in sequential drifts with shotcrete and spiles used also in the face. In some cases, longer face spiles with microfine cement grouting and micro piles in the crown were required together with consolidation and sealing pre-grouting.

In some areas of the north drive, the primary steel fibre reinforced shotcrete behind the face flaked off. This was caused by the biotite schist encountered and was largely mitigated by switching to steel mesh reinforcement.

In addition to shotcrete cracking and spalling, squeezing rock conditions caused rockbolt plates and lattice girders to buckle. In areas of more than 1,500m overburden, stress release rock bursts occurred at up to 200m behind the face.

1

To manage deformations, adjustments of the design excavation and support classes were undertaken, sometimes within an advance cycle. The largest deformations were checked by providing deformation slots along the tunnel axis and inserting lining stress controllers.

The completed tunnel opened to traffic in October 2020 with extra effort to continue the final construction phases while dealing with the coronavirus pandemic.

Such geological conditions and encounters are the reality of excavating infrastructure projects in the active Himalayas and all open face NATM, drill+blast and closed and open TBM methods with or without precast segmental linings must keep these realities in mind when approaching new underground projects through these mountains. n

TunnelTalk References • • • •

Epic TBM AMR water conveyance project Automated forward geological prospecting mounted on hard rock TBMs Pregrouting combined with double shield TBMs Follo Line railway TBM construction in Norway

Purchase your copy of the

AMR Special Edition from our digital issuu magazine platform

51

Direct by Design

National Special Editions and Case Studies Jubile

liquefied

Triumph

W

s and

on:

tribula

UK FOC

SPECIAL EDITION FOCUS: UK CASE STUDIES

20

39

UK Focus

58

S o ebæ

D

k linkerin anyconnectivity man Denmar hG rope witEu nbelt

D

k ar Denmarss the Fehm Linking acro

urin link and the Lyon-T and Italy n Austria Italy. route betwee France and networks with the between transportation Scandinavia corridors ally link most marked land-based core ea driving the ions to physic xpanding t of the nine a vital key. Its round, unders globe is In aspirat n, as the longes rk holds es d for underg breaking megaacross the Mediterranea tivity (Fig 1), Denma es the stepping-ston the deman and increase in ering in history. Record of EU connec archipelago provid up its responsibility excavations, engine and drill+blast creating and tunnel peninsular to ls. Taking landfal outstanding dinary dimension are under ty link drives, trea fixed and TBM for theed a continents tubes of extraor k and road and spor t sign , across immersed Denmar n nations era of global of Tran via vn in dina links betwee advancing a new an Ministers byha Scan of Rød Germ dividing straits,ion. between bridge and towns ish and corridor coastal Union is leading railway expans ided , the Dan een the Europe including antransport , dec 2008 ity, was theefficient interconnectiv ofan solutions elt betw rsin ember and study it In Sept possible anddrail and the membe link transportation on the Fehmarnb to build ing for ber of STUDY: across the Europe . Base y to t sort of link of long road with surge the miss a num CASE advance gurations global ides started in Norwawha tedwith the a link prov 1970s confi the fjords thestiga in inve structure one of the rent any. It under Deciding s and into establish and starting -1999 ay. service of diffe the infra n, Germ the Alps ferry railw r and n of in 1996 Tunnel throug nshand trackive expens satioel of wate links Puttgarde study andble ea Chann reali bledou d) optiounreliaa rail t pe. A ain strai borereplace l and the unders a wide g ofrova e mount d and and Euro such rway and with openin UK. Baselin ent app moto rland and (immerse and the the 1990s ns to span in Switze tunnel l Governm n France four-lane tionabetwee link optio developed r Baseline link truct a since been now on the Brenne of fixed rds bi-na to cons sonhave es pari routes ey towa d. continu worlwork and the journ y and cost com Spain the s of ibilit rs for corridor a feas network corrido across shipping developed Fig 1. Core busiest connectivity rn A/S, four-lane purposes. A ride on transportation continent with ion, Feme for a an s the special in-tunnel safety and emergency of the first avia- estimates r organisat the Europe n acros window at the front owneScandin system cost of the ectio longest andfirst thesh Dani line conn metro rsed dtube the metro at the panoramic the civil engineering design of nsr the and therom detail desigof imme railway planning al Corrido d the a perfect view of in anundergroun 0 Medite 1990s, eptu in rkthee and into the stations. two-t n rack concrranean considere Of theplan. car provides Copenhage BER 201 and linksavia Denma forof ay network. tunnels and junctions the been to the ed bridg integral -stay highw been NOVEM e had favouredd,2010 of the running . details engineering undergroun a cablehas, the bridg 25 arethe lines, a nose sea on Of these MAY AND across four therefore in November tube has it by elt for a current 44l.stations n and d STUDY: of twin-tube tunnel tunne 32km cost estimatesthe immersed withoptio When the undergroun CASE nsive and the s the Fehmarnb connected any and in, expe 4 to the Germ with less ers are extension of Line acros e. tunnels. ment of result ark and n or €5 TBM running bridge he numb in 2024, the bridg Announce a surprise billio -stayed between Denm Sudhaven opens ate than s the uced n A cable t US$7 estim adopted r prod Metro will be a acros metro ectio the (abou the the lowe n nt aof with rsed tube eing theDevelopme fixed conn 8.5 billio with s It is based uctions revealing 44-station network for an immen. After agre s withinadvanced operating criteria. hannel obstr advantage in at DKK3 ered light billio estimate comes principal team 32km and 25 s electric-pow shipping-c one of its DKK37.9 r 2008, two while the on a driverless are nopicking n - power from less at billion) optioup There embe system,tube slightly rsed s therail train 24hr/day, 7days/ strait is concept in Sept rail. It operates link acros thirdimme a link two from fixed fixed varying -rail week with headways to 24 minutes at rsea road and Germany up of the unde Denmark in to four minutes and run in both directions Fig 1. Route lt to connect nights. The trains to free up the parallel Fehmarnbe one tube at nights e operations. The tube for maintenanc a fully automated by trains are controlled managed at two control computer system south e depots located and maintenanc for Lines 1 and 2 of Vestamager StationLines 3 and 4. for and at Sydhavnen

51

TBMs in wake of

syst

starts with em bus tunnel s

ER 2002

A

SPECIAL EDITION FOCUS: USA CASE STUDIES

USA Focus Vol 1 Ca

W

D V

D

N aga a hyd o on c Aq ed o ve gd M p o ec

Vancouve d ves T w

R m

C O m

C

w

N

F

T

A

De gn o

A

underground stations In concept, the platforms that are have centre island edge doors and to protected by platform spaces are open to the underground natural day light the surface to allow there the running tunnels platform level. In walkway linking is a continuous sidewall passages and a cross for regular emergency stays on at all times lighting system that

T

B

nd engineering Undergrou n Metro ed link arn fix tral to Copenhage Fehmcen ge for

id

beats br

attle LRT

VISIT REPORT: SEPTEMB

BM tunneling and is taking the Twin mined station excavation Cities first light line beneath rail transit Excavation runs up the Minneapolis/St Paul Airport. to 70ft (21m) beneath terminals and taxiways the runways, the area's expansive of the airport, making use of cap of Platteville provide a natural layer of solid support. Limestone to

D

cha enge s

E

Tunnel

Undermining Direct by Design Se

B

E STUD

UK FOCUS C

UK FOC

CASE OCUS UK F

tions

CASE

STUDY: Excavation of the first Minneapol out of the ordinary is/St Paul LRT line for the time. It required to the Twin Cities management of early application airport was a project the tricky transition of a specified dual between open EPB-open mode make, and was and closed mode TBM, with one of the rare occasions of an a decision for use of a Herrenknec the contractor underground cavern ht TBM in the USA to with a flat crown. market, requiring electrical systems It was also the first professional adaptation to comply with USA power supplies of the mechanica and safety specificatio l and ns.

SITE

Most of the tunnel and fine to medium grained, station excavation lies in favorable, St Peter Sandstone, well-rounded and uniformly graded a deposit that extends (45m) beneath the some 150ft limestone. Groundwate sandstone, about 2m below invert level, r lies deep in the relatively impervious and a thin layer of Glenwood Shale water table in the creates a perched open bedding planes Limestone and in of the Platteville the overlying alluvial and glacial top soils.

Top of rail at the During a site visit center of Lindbergh Station in July 2002, the (11.3m) beneath the is about 37ft first 7,400ft long o.d. (2.25km x 6.5m) limestone cap, which x 21ft segmentally lined thick, and creates is about 30ft (9m) finished and the running tunnel was a flat ceiling to the Herrenknecht EPBM station excavation.

(152m) into the parallel was Client for the undergroun drive. The Obayashi/Josome 500ft JV had also started d works at the excavating the 14-6ftCASE hnson Bros Metropolitan Airports airport is the of the 525ft long deep topheading plex Commission (MAC) STUDY: An team x 60ft and the design for the design-bid-b ning, com extensive Seattle 12m) Lindbergh Station. wide x 40ft deep (160m uild contract is x18minx began light rail city plan nsive option led by HNTB network the Corporation late 1980s with specialist plicated the Seattle and it is expectedThe in subconsulta least expe of com with excav nts Hatch Mott downtown MacDonald is highly abrasive running ation is a story to provide the lk geology. and ventilation; bus tunnel for tunneling The alluvial material of cutterhead toolsadvanced tunnels of the LRT pass directly accommoda of CNA Consulting project s. Today complete changes beneath the pressures and across the central te airport n Cha four mandatory both metro the USA highAusti hydrostatic that at least two in oulders, lace LRT alluvial valley are tracked by athe tunnels bus beneath servicesthe taxiwaysand The contract specifies s Cityp moving exclusion will allow of NATM the were the treacherous favorable and mark(Fig 1 toptrains will be needed. zone as the TBM where conditions right) and electric in abrasive alluvial materials on the underground comm of the Dalla application the beginn with man entry inspections in areas TBM tunnelers ined the tunnels air pressures of less extens on diameter. ing of severa Y: The story and another comb in greatly conditions awaiting An order running Diego under compressed Transit, includ of thations There San STUD of or, in E size the l TBM intervention ents project LRT safe were corrid ever CAS outfall t the and ofand ing TBMs erns, built. system the, deep placed for two new hard probability fornot South Bay ocean ghou arrangem LRT station Sound we visite too many station on the highconc While sourc bar.

Beaco with Herre to this was nd throu n Hill underg d the two on the the extens the LRTthecost than 3 funding Added borhood machines ent ing supp nknecht rock gripper mid-1990s. n ofthrough n and AlpTr ion man entry, Herre round for the U-Link signe undergrou south constructio desig andthe TBMs was ansit Lötsc and neigh for the developm for an air assisted During activity Tukwila nknecht rock ly of two new for an among ntal during delay and Northd a lease to ing and project WCSO said the shaft. possible chance Y 199 2 the cant as -debated seismic contract Link service 2004 rankingin this Link agree hberg; TBM TBMs work environme life, plann projedrives signifito tigate ind,”the ed The first is in Reach 2 at about 3,000ft from Mike Robis site visit, design d the driven ct in Switz . Time extens beinves ORT: MA n on its much h 1992 facility’s ions; s that share mentand licate the ing is the critica theHerre resulted s tunnels comp with IT REP Dallas-bas for however, Marc fact actio through subaqueou ns weretunnel erland Eastthe Nanc on, Resident first point space difficultntly optiorailway the famouthat Herre rs, thein Canada with l facto and of the 3.5 mile long SITE VIS began seeing real system in earlycivil contracts most nkne y Cree Constructi of contact St Clair conseque with the us t to DART vario TBMssinMount nknecht highw ray and in assoc Huitt-Zolla k and fortraffic run under and geological section through complex port was this contr cht in May two the 1990s, along on Baker Ridge in Denmark. nine mont could comm allas consultan erns as Presi Figs 1 and 2. Plan dent ofproject thethe m of railway conc iation withWest Area CSO Manager for with the first streets act public trans Creek facilities tunnel to outfall, which passes hs was otherof the Storebaelt SEM tunnel Bellevu light rail dbreaking on ile starter syste T) LRT. SA andBob project Zollars, and general both projects EDT for manu a signifi itand building and the South Bay undersea of the Pacific Ocean e floor . comp in factu For the and Hatch the cant firm driven (DAR groun Sound in the two beneath 20-m rers. After Line’s new it onents act edge on with Mott MacD with Delo management with JJ&G, the Seattle Transit LRT, 11ft i.d. machine y, built alluvial materials of the consulting taking n Ham of the Nanc run from Rapid Trans million contr milesct.long, the busthe it all started bottom in mid-M 3.5r proje depositsto an in tunnel truction Expresswa delivery offers from iated At nearly s Area mix of thealluvial a singl onald for WCS pton Asso of the 312ftay, we plan y with the starte through a complex end of s. for cons 67-mile Dalla work on its $86.8 of the TBM water recla its assoc four-lane to launc e site office The cut the facilities plan studied ciates , tunnel a ages. n is thatover passes O. and July, the d (95m town n from Both licatio h tual s ent deep River which will the first 1989 starte ) deep a implemto statio ased location even projects and the Tijuanaincre constructi mation cente BER d inestuary to by comp TBM Rock downipal the be ahea Chicago underground while acros millio of(P/CM) washed at town McKee (CDM). mouth SITE VISIT “We RT: nOCTO depreresse is to beofat the The princof manag d of our dale Shaft by at tunnels on itsREPO be down Healy of flows fromon of the pumpr (WRC). At one the R.M. Claytare Dresse thes, seabed and r are, in fact, is to to from sands Camp REPO RT: lth baseline VISIT $18.8 Cityplace runningSITE the ng composition . granular 6 by andclays on Nut late 1950 on work onwea end ay statio d the built runni River the 1985-8 and DECE shaft for the of twin tube y ahea progr cons Comm of silts on was Nanc and freew m) n is unde fine the Trinit sinking MBER d of sched tructi tion, am. of thefrom secti sizeable y Cree ado starte -lane ranges 1987 way. cobbles shaft treatment plant grew, a second s distinc and rway to WRC eight (6.5kin which High path 3.5 miles elps of Color bridge over the capital city the WCS on of the new, k project. dubiou gravels mile sewage of the the region the deep alluvial westFrom a 200ft being new underg element and site mobilizatioule at the mom first oston, theestab loose ofNorth the 4 kee, shares As dedicated At the otheraccept ess the LRT ts,lished forMilwau After primary Boston’s etunnel fromround Hensel-Ph 1952.tion MassAna O project will anticipated. n, but minin ent with we are succin has arethe rity, chuset 1968. nd each the in to build boulders street Seattle and the by Quincy Massa been treatm the end, begin autho d o large beyo outlets act in futur looking pora Island shoreline, ’s the the ing just charge Chicagss ont . At the answer toTBM to for Island contr ent buses and Transit the seco is sinking the back from at Deer the ged through short for 60-70 g is the critica withit has cities by incor do 1 mile Formation tly built toplann Parallel 1.3 TBMs WRC site, plant for along network, urban rema Diego in on only set about round Sanfican was een proce l waterfr thesigni Discharge ft (18- 21m)/ s Area Rapid LRT y (EPA) thethrough week plant schedwas betw -the-ctraffic an uphil nd WCSO TBMClayton acce mile ating US pass under the Agenclace, to belowisofdischar an long maximum.

(2km) , day rge with lock onconges ule. We “Ideally , the Dalla a closed, 230ft frustrlarge the waste ncedand designed those ems, ss shaft Obayashi/ integrated ation l gradient tion. about in beention ing,1986 a fulllong discha Cityp streets Protec will mile influe often among ns probl the expect tunnels At sion pressu three seabed the screen will is be For DART manage an by excav day the one recep the of mental from and better to 50% of week uling theends , up 8hr ent courseNego rized tunneli operate below provi to the s. tiatio than leading afternoon in for ate 23,00 central district which Environ n caused to 158ft in the watertion shaft to have lopm shifts Station more 45ft at up harbor. the buses d the the tenanto federa expensive et . Part of main deveits water and lsched is a main of little ages in y. in 1983 thes,pollutio shield Shaft will 0ft (7km 2). n.

(65m bearing .ground statio The ng215ft n issue present 4 ce on each/day, will 1 and offtenan In the waste out of the 6 days/ about ,” said John the agree would e into (FigsLRT the streets ) deep Jim once a day take eDART Budg someth arduous, ing the ,agree nd pass desig sea level up advance first mile/hr place TBM, sswa ded. rgrou south North Aven) in of anand dissolv ce contr and techn takes mach a long, at this point.

Atkinso rding to sewag MacDo to its 148ft will carry ing and iently commu ment mile/hr in increas s and tideive Pionee 20,500ft oflaunc ician on accotreated nald, Project and that this is ill-foun the Expre plannof act with tereach hedr at with Herre inen,on“but there e the loper elmed.

DART: to dilute n with unde ofebbing traffic flows comprehens peak with athe insuffic s, but and deve period (6.2k er overwh the Rock ue side that to arrive with complex s proves many are (45m) deep nt forl abilityat Manag Cityplace delay nd statio studies mach nkne been s. nkne to one Herre full-tim ’s natura sky r of beache investigation about either Parsons infor sitergrou sinceunde dale Clear Cree m) chtscrapers along deep tie light an enience backs on the designer 12 e Herre Intensive long and time The , owne Manageme green n on better excav together cht. We ine. We also have rs, onethe Waste anchoring by project on harbor withnkne “Two TBMs the tunnel pany cally hassyste Tunneling these k the uphill gradient prepared 7-11 conv m beral finishbased the solutio high costof Constructi reporttowe chtwe need easy will the LRT a majorit both r began in ated and they date, in as far ofas can tion shaft geological to prick are a minim route and recep hland Com waste biologi to re that, chain caused tectu the WCS access group r contr indicate Atkinson/Dillin November will supp pay a fixed cutte of s, CDM to t outfall. To outfalls y act archi . been given of the startedate.al the Sout Science problem and of the tunnel Director ational rdfour ” or pressu reaches to theum n, ties cost/yd g the Assembly requireme deal 1986 when ventilation effluen d ly all the 3 intern face. retur gham authori Martin, excited to have construction chose Knowinthe by the isOintunne pass through individu Engineering 1996 s and lowest of of rock JV the public completed Also, long-di two open-fa dry, lscompe the Guy of thewill asntthe cutte to lie stance14 long sea tunnele ly under uledan the t tunnel work and said consent ibute 1towa oving paren to get excav an avid it takes nt 3 are eight compe ofwon theTBM to get predicted, first F r need civil and case, contr tent ground “We are contrac hold treatme and machin the sched of large, slow-m s.” the upper saidced current decre other below the are about byOften Bostons,’s t with the ation wouldforReaches geology.

Ken at Rock are ready only inn. which there water millio with e facility h, with deadline the, we Johnes material part $61.6 million ting bids at $44.2 the largest theaction. quite Indifferent breasti 1980s, dale Shaft store sible operation conscience into last and t $40 the in oper of WCSof are n whicand ng plates taking the more respon face ston, sandy d abou of 7 Nove ingravelly worldw be ide, ated ia.

O the thewet ation and into contr tioncost to mber softer scale tunnels much seaonmust usual 30-to-3 Engineer’s Estima million, well , theOf the statio porous City’s Proje in agency of the gripp act.in“As operati ofgranular Founda forcengthem rolling , Austral anaestim nts, willpressure in theervarious runni a the State a job of this on.

6 month constru te. Instead sectionmachin ons.” in hydrostatic 2007,” well as conditi in Thefullvation on sued beSydney ct Mana barLaw ireme to was 7requ jogger and Agency secti e. lace ction ed nt Conser and its beach of ion the scale, nd going anticipated the n The Cityp are constru was “techni s. edown Protect 2 and 4Act me, ction period , Seattle Metro, proposals, TBM drive ger for the all treatme tight 17 month statio m mentalReaches the schem now involv under ing costs undergrou forservice cally syste the one from material sewer Wateral sche silty for s plan has with flow from expected. the client, s, the contr and sals progra Cityplace nd sections propo only e CBD is also Seattle superior andwith starterl Environ origin permeable by early l inches ted Robbins CDM facilitie Federal Clean the )Federa r Island a town r theless the reduc act Federa (32km 1972 competent, eleva sued -based making most econom ed ,with 1990. To m to have the system imposed a Apart of the 7-mil to spare down Unde turnmile on Deer an Island in Boston undergrou n of earlie 20 ng themore State.

In charg ical.” the y on n Deer meet place t reliable the in enforci (right to Robbin ) by pressure. in was deliver on not the (EPA) for(11km this, Atkinso millio service ary machines, s ) moderate harbor by suing at abou y easy and ge taking d Expresswa more an order DART the $218 d when down versio sal for atedded this secti The machin and second n neede one and deliver respon quick. t 7 miles impose ver esse ity rundischar propo was EPAestim 3, thereunder es are quite 1989,ces andcarried 1depr ed quickly for each tube, design d two Island ns howe After primary 8-10 miles out to in eMay 1986 InResour was to of reaches and thewas original rground for abou schem of the nAuthor Nut open-faced finding different . conditions long tunnel. ged estio (CBD) and expe nsive the t and ed, built suggestio . The median mile gravelly Water e excavation (7.6km) porous, rectify rtmen district the a sugg foundIn District e theTBM an CourtMassac ran unde plenum, will be dischar 110ft of water where 5 Thesor m to abov the backho shields. To provide from the more familiar The geolog to be husetts progra effluen business oval for such s the In t using a no ture into the way median. the Depa man e paddle nt, de can freezing. ent y be High strucentry which had llytoat-gra central limits in about can naturally dilute of ground on the treatme implem -type excavaoptimum face access tripod of clay with the is mostly over-co . Appr n. the assistance a alternative ) antia had the harbor inter-re the State .beyond ocean without nsolidated to require 1999. millio or at grade water table .7than (MWRA $1.1 billion cheaper chamber, subst no$828 of the is expected sea built two other acting hydraulic tor is mounted on , ted by ment entry sands, silt 14 of Pionee runs 47 balanceLRT lineswaste (Fig 1). and rejecman d at later 4, safe n by and cylinde a ruling r Square Stationrising close to the and thetoalign machines face. ical were theecolog situatio denied now being built and reaches 2with Theremaining is price Washington the court along ed.the water table to this design rs. Robbins has surface south the air to help by holdthe (Fig 1). North rade There will reach DC Metro complyof compressed is of-ways residents side of biodeg todegree , one used scheme Coordinated e was and of the Station Caracas Metro worknd. y Deer Island facility in 1974 and over consoli well below the tunnel thergrou either rail rightromis on the sswaed unde time to lose. newly ,formed , the the other scale busin be of noess boxes in 1978. gallons/ dated materia Expre existing elevation The to e left propos thethe , the 1989 a comp used on the has central ts dated in ral and the dry ted, ls can be thedeadlin sswaydivision on costthan 1,200 million part of 37 June a short nsultan system such mmo ement In its very hard.

Expre sub-co When integ comple acco The 21ft (6.4m) manag y of more l and constructi mral ged ative. From lace the Cent erciaers d be atedcapacit progra Being anhave own ts enga a peak woul Engine diameter, (HNTB) g. and estim comm North At Cityp ptable altern sits r an doff a ultan Kaiser the y thrust cuttin d was 140 ay onstructions, with tonne, 600hp capacity of a majo multistore engage by cons n & Bergen highw truction boxe is no acce route follow Cityp lace, MWRA 2,400 tonne s Tamme mme/cthese two shields have designed their cons the Needle have s rising itsa progra via the 20 project, million, were through Howard Both as district, comp t and thrust rams 62 built.1988 April 19 passes development in be t to Departmen y program. of $189 yet which Geotes ential Highway which is plans.

Expresswa by the and resid second of ed in the y the 7 DART LRT incorporat towers, Expresswase ct on the Central major impa North and inten tion of rtment, reconstrucHighway Depa State “Proposed Texas by the

Boston H

gas store

Extensi

Y

e Line

Y

A

UK FOCUS C

Y

E STUD

US CAS

Y

T

ASE STUDY

F

STUD

el

W

US CAS

el Tunn

ASE STUDY

PUBLISH

Chann

STUD

ueduct st nature ton Aq htn again Carsing Ma hindsig in W

inrou spe erg nd ed

ground outfall in difficult Driving a sub-sea

ce LRTexecution Citypla Dallas planning and kles arbor spar

Killingholm dheader:

e: anBrit ain’sstm inve first ent und

collapse it not back CH 1999 under control after Authorit•y Construction Manager: in now why was in-depth of an Water ED: MAR subjectTrent works at Heathrow is theSevern The to•that Taylor Woodrow station excavation &Safety being Client:the sites.answer now UK Healthr: G nnel portal H Hill & Sons tunnelling : Eurotu faultless.is ners: Contractor: investigation by about October 1994. •The Enginee the intended of which is ingreport ofClient • Design-build ENT: JULY r: Geostor the The £20 facility in its Desig Consult projectoflooks vicinity of men and 1983 when •(HSE), the & Co of the site for the depth andtunnels out uced from materials and for million project, kept million yet.

• Contrac carried e Ltd simple”, undertaking the and andExecutive Mowlem 78m actor introd (TML) Balfour Beatty £15.1 is “amazing d 1994 AND machinery ventilation, with John months taken for several tors: according ass awere Contrand maximum a joint wereLink of Calor deep x 1.8m diameter of • men bore hole reamed ly coal interest, (6.5fissure started brought to the application Contractor: being collected firms to•appear samples to Tom The Resident Gas,a with hatlling system -Mancheby eight unlikely andthethe FEBRUAR surface via two a 10.5km h the wet • Thyssen and Conoco,with is still Paterson, Wirtha reamer Trans 160m. Core is impressive 60% consists Mining Engineer to build tion (p56) the start 14.5km 40% tunne were complete /Pigott Consort l throug Carsingt resources aton Material evidence highly likely long spine roads examina Y 1996 contract of legalthe tunnel ortium contract . The top . ners: t at chalkproject readythe to tunne possibility share, has and with gs.detail for constructed in as a result remains of alluvial ium: Shafts to remainin , causing view, the meticulous. drop coal isCons l Desig from • Boldon 20m site and the identified proceedings al in headin the ls) production onto hard planning to store g the the and glacial longofaqueduc rock well below the upper geologic Tunne moved through the tunnel Tunne attention mile)ions ct Japan was Drilling: Service point of that ethe of the a conveyor g foron next 200m le deposits and the coal bearing scale rtium landward the in the crossthe slightly to avoid stages and instability tenderin u d’Étud into severe indicated availab technical Tunnel to conne for the parties involved. made clear toA conveyor adit chalk strata. remarka condit is the an event for transferring boreholes adjusted • Conso • Fairclou While (Burea ire has run sea andofnotexcavati through borings t to be or struts and readilyon onto aon to construc rom a system will bring which stretches Upper Cretaceo conveyor hen gh: Cavern bly quickly. e: BETU ion whalings in Derbysh alignmen in either their under Channel Calais in France Therefore, it was the driven mostly the coal the spine tionof nald the early The Francbe us complet g props, isedup the two 1-in-4 need for s were tunnels Jubile theunderlyin east under for the roads and hauled Seae and to ofs, andsystem be used area.

McDowith wouldshaft undersea avoiding d to In January drifts to emerge areddifficultie years behind have the North attending an all-party-organJune to Projec affected Mottseries tunnelsrescue the surface could not Denmark as two journalists t team, Lineinto UK: Grit updiameter at the was Exten in Englan 8km at Gascoigne1981, contractors would Gascoigne Wood 60m as comp ng in beThese TBMs water much ean end construction. angles t, the of as Dover briefing in late may granted by Woodplanning six exploratosion and (Fig 2). When Fullface Ashover the Londoallnonfive From appoin site where all the permissi andthe French at shallow Germany. amount may to Europ dateand l and h the lt projec JLEWest It excavation visit and technical was Glanford of core constr ry coal formines budge Under throug ease Strait crossi to the are producing g tunne a difficu natural ground is also necessary to e, planned pt that of the large of access site uctionCouncil es, these dipping the excavati about the causes handling, storage and loading main series groun t as thedchalkted byborehole at Borough ent runninThe ls. NATM because full capacity Seikan schem passing originally1970s attem use the was not well scheds, it was found contains several ofby the water pressure to manag on of theextens facilities 115,000 1996, that questions by mudston equipm late 1980s, Selby porary es n for marine would as much. lty , awarded of tunnel. are located (Figs ardoftunne chosen theonLPG.” s and the lack bands two approxim ion,million mudston new of Applicationas its progra pre-grouting. e cover ule. deliver aquifers 1 and 2). to contain with the or along lengths greatg difficu m 3 caverns will from and the costs thereof g tunnel costing twice 10 The mme setately expected, the contemexample. The UKedlandw cular fashio strataspecta 16marl contract and collapse principle specified and tonne ions had the a of runnin long very km-lo es, As coal 21.2m the however the 53-mo under soon , for ground a x rail for Conoco for year, mostly for use startowned tunnellin is as spine roads reached in isolated d interbedd assoc ng hard more to contract s are: i.d. land When choosing sandston to do long The journalists tunnel The fractu water nth red condit (Fig used in and 164km Japan face bytothe public pressure, • that a higher funds t, except the storageset itself Authority programme a madeflint Central UK the Electricity not be by openin first mine at Wistow, lly answered. time. two 7.6m thensiltstones service one containe on the Water to the 2). iated cost , acts increa to in this storage Client of drill+blas Generating ofBoard of the survey 2was ed with section) x against at that twoletunnels, case liquid a tough central thorough briefing for achievement interbedd g, it knew coal production and butane gas facility, the ofsite : JLE also specifica Severn Trent 285psi, comprising an UK The use propane thewere ses Governmen at nearby LPG Transp chosen, calls for 100psi needed geophysical Marl stratum task. As theSite diameter were treated to a from excav power stations.(Fig 1).

A ation ed by high (252m 14 large 4.8m i.d. it had geology confirm the 55m Londoto Manageme work er. It was ances, was ort throug propane tochamb other notab connect Chalk Mowlem view of the current progress and to a visit it began with tunnelling of the soon weak, most t Depar began immedia vice versa. x 15.4m investiga In time or is large the Two civil John the and a n circumst perhaps liquefy the and French nt 4.8km, as importan Unde the same bids.

30psi in eable, spine h team constr tion let in late project’s tment to liquefy the project's to d wide the continuing to which at the crossoverthe design of short of roads In the interim thetely rground on 1). the other containin out due from the success the first of t consider ation of pipeline uction for • Contr and later the gmajori connect the remaining million contract butane, public fundin shaft(Fig conveyors 1993, into various sections four sea depends 3.6km and it. The was aligne contra lly an imperm excluded Ltd le for rapid also scarried under in the a signs • Excavdiameter excavation spineof to sinkand Its aquifers £2 “One ation. access ty ofpresence of actorsthus how mines. cts borings. During tion, ls under e problems expected aunderground at theg acces for investiga shieldwill transport a great natural is genera fourconstr g is grante tworoads deep 140m of the most tunnel al workin access for each highly suitabzones awith major geologicwas to modifi both enginsubstantand 3km of the 1.6km x 1.6m uction specify on-going works. Knowing exactly is essentia extent 66m which extensiv from aspects shafts, rail tunne the work princip engineer cavern, was main site d. ial their desig startecoal minesalong te to us rock on impor al propertiecation used again ed as they come decided to l. “Unlike eers: See a shorter more gases, excavation d.

Thyssen as the g and three on line andawarded ated. is also side workmanship andThe south drift tunnel is being Roadheader tunnellin All following the longto land By from s. Petroleu clauses other tant almost all following n-build explore inclay en-roufaulting, it was muck homogeneoalthough fractur be anticipThere theto end consultinsea of severa the contra stage, g jobs, we current quality of driven the /Pigott behind alignmeasily constr the of form, themore Consorti m we 500m on method. best the the site. what the 5.8m diameter borings soft in gault end. The headings. to pages tunnelling of water option, three under from with stored welcome l the um. uction ent 5th introdseeping Januaare ster.

Nine to two lofterminal based excavati Hill in ct tunnel the docum takes sump entaryCastleadjacent the sight s for eachmachines tunnelling, inflows were uced into surface Robbins TBMborehole downstream for itsof Manche supervision differs liquefied in their workdeadservices ry liquefied total 230-w Tunne construction with be ent was was in a large supplem neveran average of considered stratum headings. will based cavern landward tempera 1996, the by eithercondit workscorrid and end levelH Hill & Sons continue!” into the ions, is The need to cased about 100m/wk. the collapse may Channel was moved and or were orted to the scheme eek corrid long tion it was the ground high waterthe Chalk Marl contra lowering booms were fortransp on confesse Strathclyde drilled or by compres programmeweek ture 117 of theira stipula of Anderson nt would Theconventi below seais G or beingprayofit up to 90m the UKOne portal was going on before Boldon north where detail were made.

ICE conveyor by d Paterson included surface, n also is: the implemctor in the Drilling under explained in some tunnel, some 70m parallel, its originally Coal Board tionartthat Souththe out sion.would Site investiga and excav three the shaft wide, the muck was Tunnel Following a maximum 115m d. Tunnelling . equivalent it is usual from of site andentall equipme using portals grounad On the 1979 ofand l mentio be bound The incorporates oil well type is being 57 x onal 75% comp known, but it was times the be excavated using line ed to National plishm theselection lies during to ation to store ent 16mm the pump stratum through this out in familiar sectio of speciaarea of surface steel ropedrilling to accep ydistance m3 some the seabe a Titan 134 roadheader The the bottoms water along and accom flamepro now being progressed alignment to approximate themanin accele in finding for thet caverns e ofed lete. g incarried refrigerated provid cords rig. n was tunnels are going detail how downhill across the full Worthwhen an Of the the ration a beneath making about half and ing y of the work width£4.5 ly about tanks rather 4.5 ,million the tunnels The JLE depth. to workin available. of deep borehole whose is sufficien of themillion d with at a1mlarge intervals tunnellin pressure logistical necessary servic site 30mm thick many the rate of progress was awarded water inflow progra original. slurrie and 75m suited UK s as strata, with the possibilit belt.g The t to containfor contro vessels. Cheaper and that it was sinking standard contract planned • The Projec thanshown Anderson construction al in in so at Strathclydeto Cable the ce.

Faircloug is different from the t, generally about 50m/wk. Coal in distan t team g the to be practicmme s highly tried and readily the LPGlling groun methods availab themis under was three long holes 1km h, the stillthe Measures cannot be extractedfive tenders. Geostore the aqueduc Belt for dispos as to make minim system is cost lowest ued conveyor ered.

Coal estimates great to store whilein about l shallow supervising UK side, of runnin pressureas reason larly the ising but not d movem of appoin remarkablyof d until the cross theundergro le contin North Tunnel is acontra were well the cost additiona seepage waterable g pond grouting on the scheme , a licencee ctors in largerable,” French being encount particu of adit connecting steel These used on of settlem ted ent and geology Robbins pumping company comp changed und rope Projec NATMAqueductation with several settlin ent, nearly methane capacity said Mike were accep from or reinforced specified theGiant shaft rescue trains, of the TBM from the the two conveyor which allowe facilities. techni belt t the spine roads and ted consu excav Geostocleted tunnels.

Manag on ation ofir and ground In some access The cavernJLE. have extensive designed cal doubles speed with two ls Liquefied all have Engineer also What had l advances most Reservo lting sea Smith the k, lling rapid of stable d prohibitiv bore time steel been Applic cases er ton the which roadheader obvious, canno tunne hole ropes and for most under , JLE’s connecting diameter supervis for Const tunne gases • been of origina enginesuccess and sealed, this may To comp 57mm allowe e. has l in logica start,tothe the mine above is 1. Carsing To and prepa allow grouting fully tstored the same for thethe ed a ersexcavation ers and pressure of several require extensiv supporting tunnel regime to ensure modification /week the detaile ruction Selby ensate red the tunnel completed. construc predic used initially the techno ng high speed 428mFig operatio spine lightweight LPG caverns, On leached be jeopar cross while at cing service roads d indesign projecgroundw under alling area which to tion ted settlem e for areas 1in-thick lex chamb clearly most expensive, um and breaki 60mWistow mine t prograater. “Wens and ground The steel dised by fordocum of the the The chalkbelt. a projec contra ct many years s cavities in salt t s through ropesincluding in northern a maxim a maximum 8h high,alteration the comp ground marsh record came online in April ent may our are formed amount of the original scope of works is mme deposits condition spliced regime the advan excavation where t oftogether one events there entatio grout of the At its this in size side of findingcontro g to around the toadvance under to form an France, finalbut to be almos thethat still prove have forand engineer l. the n.14.5km built in the construc isrope suitable injectio Cliff. This a purpose The and the consultin length, with the expected methods caverns of the the UK 7 days/week with eek) buildin are within proven been . Associat endless dealtwo accele geology tion of water comp concurrent er, which had of the conveyor at -built undergro each x 30m deep cofferdam in three stages:diameter too speare will station g side. unfore edOne be lexity, come intobyn ground of the shift/w the contract and water contractual ration construction ntally the tunnel; easydifficu of the airport seen This is done of itsits und clause most advers no s include at Shake al working treatment (24h/day, maintenance kind month task, as longest used to curtains groutingalleries water. ation in operation their own. over chambbefore arrival excav of driving Central Terminal Area (CTA in of g methoabove, the e in Europe. ete segme The is useful s whenfacility TBMs lties.Paterson explaine South Killinghohas between River Humber, a newOctob LPGerjetty Two effecti was“The ds used caverns.

1994onof re in advance are built; and radial 1, 2 and 3) to almost totally permeation the princip of the six downtime service Similarly, pressu the collap over the grouting olted concro.d. 8,036m. geology were being d:the recove ness complete on lme, and At the nes. ve d. rings NATM the site neither non-b pipelines marine Terminals on must on the the ry progra of unrelated, se enough connect the l of machi negotiated.” water as the groutin JLE includ grouting be compete excavation gallery strengthen ges and grouting launch a fully to remove the extent tunnel muck will also km each is expected has been complete nor g, mmes Airport which facility to sea tunne 22km of 179m/week nt e concu work extensive excavati encompass and TBM allow the Conoco loose a to stabilis Express but ofrrent, Only by cross passa had to share cing after the lining vs be necessa course and 18.77 Settlemen and to complete lined under l average was l south. e and water disturbed ground. grouting of the the roadhead refinery Rail er on and the Because the geologic Heath compensati an immed also ry. advan 17.36km collapse and the tunne rowmore and Since limited the t cont requirem g ducts al propertieon groutinbearing groun l site are so iate and Link tunne introduction Groun with the the effects tunnel, best overal running ent, the drivesstanding at the edge of this huge excavation rn slurry relievin projec support A Titan E205 of the Jubile s of rolthe d movem the more responsible l progress l to porta n times gs.

TBM, marine t. As g for mitiga d, of predic bay has been importan t, a geotechn roadheader e project ent side, mode pressurised econom ratesbeen consecutive interce job, Mowlemscale be appreciated. "The upper the UK induce in the from porta ted transportatio g tunnel headin Four which South ic its contra one French establish excavatingteam volunt reaction, the Tunnel the have dpiezome its that bid the couldWork of by excava Tunnel e (EPB) and ed,pt ground ical volume losses ting work runnin On the the 9m wide eight firms arily instruc JLE projec the most critical tender. ters tion has Channel cross marine water-bearing ground re balanc Of the Waterloo ctors to stop to measure equippedmovem mining with ents as and x was soft outer lowest 20m second tedtop heading four hand 53km long and Londo thethe and through NATM 5m high ground water they occur. beneath t team. The Line, concerns for the and earth pressu many lateral Compen stabilized by 1.2m with shaft ducts won of the integrity er 1981 gravels work at ,some d the rescue • The x plishe with visible is supported and running 30m deep central on years.

Septemb section re relief access sation and safety n Bridge to of the oldest bands important as it does 60m diameter Comp ls. in shaft, pressu accom original ed in four piles which interlock review of marl started 1km of 19m diameter grouting tunne Fig 1. Trace of the Geological , historic of the and and flint presentensation stages of diameter the is on the one toSecant NATM ges and main bored to be complet different works. a comp ally most Alan Powderham, under grouting and subjected prestigious, the only work had designed for JLE in the About centres," explained all of which were access shafts superimposedpassa areas of lex chalk 1.06m tunnels, and to the is princip techniques Mowlem plan was the four portals the three at that limitation exercise manag London, outer platform linking of the Foundations time and been completed NATM surveying yed The from ally to ensure ement tolerances most stringent concourse and dersDirector Managing work collapsed advanced a tunnel roadhea decision-ma and co-op in multi-level thegmain tunnels damag the works of Mott MacDonald restarted although revise the delay headin ling projec ever before • The ce systems emplotunneldrive excavation when Strathclyde Geotechnical Steel Division king based erative all-par d in due imposed e provid had a ea t in the Anderson fact representative on Grosvenor guidan Asses In using ct designer's and dama unders ed on city. course lead ty sea. in sments six Aquedu and ging effect by extens on inform Markham , predic tonthe convened PortaltheC instrum of all buildin under the mounted that Carsing Compensat servicein ation Solutions Team ted on the started at the so-called entatio ly meet French gs within of the 10.5km n and ive geotechnica Tunnelling ion grout the 12.4k 1mm settlem B and D in analysis. collapse to engineer m on did actual the UK and the shields. the ent conto 350m cross sections ing arrays m under l computer-b and at Portals immediately following the “The of dinal and Harris, ur along ground way forward. "The junction was within February 1982, at A in April. under ased a Direct aim,” explai and in economic Fig 2. Longitu route define the Westm a safe headings level. ned David stage, or of the by 900mm and finally the princip tunnel marine on March, s a inster area at an early company Clay below is supported the 60mm London d decided conditions, on comp al geotechnica installed which step in GCG as nts of It was line and create d ground diameterplan contiguous piles ensation l advise from five establishme side which a predicte r to of the 20m below, the grouting, tempo viewcliffs • The s on the UK comprehensive continue a further chalk andon, rary grout “is to keep JLE from, ng m3 e a excavati formulat capping beam at lagoon l headi the white ing shafts tomillion the method of Secant piles.

With "A substantial concrete collar e Tunne foot of ating the some 3.75 incorpor nt lining. at the a rigid UK Servic and tightly site for main forms and permane ground the surface e for the disposal what is an small roof support Employer, in all the 79piles together. manufactur linking nt of the were Report site. of muck TBM in in both the recovery ideas ies agreeme of CIRIA working s’ "Originally, Howden a large Practice endations high confined nt casting factorrecomm excavating of on Contract d based nds instinctively segme approach g - Improve Fig 1. Plan of the ‘Tunnellin nts were x 65m," said Powderham.

• The ries where thousa Gascoigne Wood and the general nts. 65m box of about y drifts and the five mine followed lining segme count shaft sites; UK factor contract documewere to tunnel Thewere tial in the Inset: Fig 2. Main ated precision at high rats. incorpor of the tunnel design features a poten day sections rock, the need for produced Grain had Although nt nts per 55 Isle of near segme on the driven in compete was expected d 4,42,7 of 1,152 requirebe roof support output immediate ced the and produ within 3.5 years. on of the 37 42 nts segme now goingand lengths installation units • The thousands of and other , track many al cabling of electric

REPORT

tax in the sewerage the water and served by rates for and cities the lowest clean 1997 one ofMAY 43 towns project to REPORT: had paid payers of VISIT ians SITE Boston ar, $6.1 billion when rate d water flowing to a ten-ye : For years in the 19080s t ted pollute contributed dramatically (MWRA) of the earlies that preven changed Authority was one programme USA. This r project Resources the TARP Milwaukee. tts Water Boston Harbo Harbor. After including Massachuse Lakes, the of Boston on since, pollution of the Great following fully assembled manyback-up Michigan up severe with Boretec and its Lake USA before EPBM the and into in go Mitsubishi behind ups the Pacific Ocean from Chica on clean shaft and site tested with t CSO polluti the 200ft deep access and larges being lowered into

CASE STUDY

CASE

from :

Direct by Design

Fullfacer vs roa

OCUS

s s Heathrow risethe mire and shine

t management San Diego effluen

CASE STUDY:

Application of a TBM for developmen in North Yorkshire t of one of the was the first use twin spine roads of a TBM on a demonstrated to link five coal mining project the significant mines in the UK. The 5.8m advantages of Robbins went on diameter Robbins the technique to supply TBMs to over traditional mine CASE operations the roadheader excavation TBM non-circular TBM STUDYworld for excavating over. Most recently : Excava rectangular Robbins has developed and an estimat cross sections. tion of the ed half the first a new cost of creatin ever purpose built also provide LPG storage d greater g the same security for caverns in JUNE 1983 storage capac these vital the UK in CASE STUD ity in tanks infrastructure on the surface the 1980s were built facilities.

Y: JLE, the SITE VISIT turbulent at . Underground REPOR T: MARC London times. storage Excavatio including Undergrou H 1984 n the Big nd Jubile and Lond Ben clock progressed e on Bridg tower and under or along Line Extension services project, side to area e mainline railwa the Hous lived throu es of Parlia some of limits of s of south y statio the most the gh exciti ment; ns; and impo created excavatio Underground and east Lond ng as passed well as new metro rtant landm on, system. n work under arks of the most s colla Controlling which until the stations the city, pse he Selby coal critical unde excavatio then had rema River Thames labyrinth mine complex challenge on the conc of unlined in four times r the Waterloo Yorkshire was n and urrent s toget tunnels, driven designed by the settlement ined outside Heathrow ircuit and • Client: UK National her with SITEclosed-c UK National Coal the techn to bring metro in chalk VISI and loading Expre beneath Coal some mana Board mana Board (NCB) TS AND terminals 190m ical cons ss Rail the flatland to connect five ging the tankers for rail and ging the • Consultant: bank Link proje ABRatIDG separate mine sites on the south of the River truction National Coal budg Immingham. impact road - at Board Wistow, Stilling Fleet, Humber, ED FRO of the • Client:et and the M&E ct in October will be used first mined Riccall, Whitemoor as• the Contractor: M TWO Calor Gas Cementation 1994 were station and North Selby. underground Geology petroleum Ltd installation JLE SUPP Each would have liquefied gas (LPG) • Consult among s. a the UK. pair of shafts for The geology LEM ing Enginee storage transport

SITE VISIT REPORT:

UK F

1994 Rail Link in October the Heathrow Express prosecution excavations on world. The criminal of the NATM station UK and across the the works and CASE STUDY: Collapse s for the tunnelling industry in the later, after working on to recover during ramification ns made engineer four years had high impact shields and its design-buildnce of how decisio aders in the experie trial of the contractor to injury. insult a salient added that the roadhe than anticipated the project, uct was complete predicted aqued The more water Carsington for the project drill+blast. rock and 10.5km long ts mining or ctors bidding right when harder The hand amoun a Contra to turn ded CASE STUDY: seriously wrong. keep large and 1996 provi as. They were JUNE aders go ssed air to Its REPORT: roadhe in 1998, under compre cts. before Christm their es SITEtoVISIT design can upservic edproje giverail on the hillside advancre c was four drives would be against publi infrastructu ader shield, out of the ed to hmarks mega forced three dwhich kept its roadhe of future , stand as benc and open face, funding ingplete lems remain l, com . ion and ed prob control nizat under nel Tunne orga water document ofning, The Chan its well 1983 ative plan well as STUDY: T: MARCH CASE el for the innov successes, as VISIT REPOR the project in truction SITEkes.

• Client: BAA role mod mista that occurred on ng cons similar the mind, for the owner: job in the collapse will always focus outstandi s will avoid • Consulting Engineer hatever jinxed the well October 1994 achieved be to other h appears remains if it is being Mott MacDonald whic beginning, all of the question then? The

ub ea nk

A 9

SP C A D ON OCUS CANADA CAS S UD

SPEC A ED T ON OCUS DENMARK CASE STUD ES 5

17

Denmark Focus

S

Canada Focus

Special Project Focuses AMR wa e

upp y d ve

G and Open ng

Fo o L ne

OCU

Epic AMR

C A D GROUND

ON R

h gh peed

Ground Freezing

Hard copies of our digital magazines are available by contacting TunnelTalk@TunnelTalk.com

w

NG

Follo Line

ne

Spe a Ed on Ca e S udy

Bos on B g D g P o ec

Boston Big Dig

Digital editions of the Special Focuses are available on our issuu magazine p atform