Cross Tay Link Road Project | Exhibition Boards

PROJECT CHARTER The Cross Tay Link Road Project Driving Forward Perth’s Ambitious Future Health, Safety and Wellbeing

Communications

The £150m Cross Tay Link Road (CTLR) project was approved by Perth & Kinross Council in June 2016 to address the long-term transportation needs of the area.

Sustainability

People are at the core of what we do and everyone’s is ourNew number one priority. We have a River Tay wellbeing – and the Kingsway, consistent, holistic approach to achieving this. a six-kilometre stretch of new Everyone involved the project is expected to be open carriageway linkingand the A9toand theIt is everyone’s to challenge open change.

A93 to Blairgowrie and the A94. responsibility to be proactive, callItit out, don’t walk by andthe always remember yourof safety is my safety. also includes construction

We will create understanding of what the project will achieve through regular positive messaging to communities through a range of media channels.

Project success is dependent on the development of a sharing culture with team members working together.

The construction sector provides value for millions of people but uses many resources in the process.

We understand this and are committed to carbon reduction in a bid to make the project as sustainable as we can with environmental protection and wildlife safeguards a key component.

two kilometres of realigned dual Legacy As phase two of the ambitious Perth carriageway ofleave the aA9 justpositive northlegacy of in Perth and We will lasting Transport Futures programme, the the Inveralmond Kinross andRoundabout. to its communities. This is a nationally important piece of infrastructure that will improve the CTLR project provides a solution to local environment through reductions in air pollution, the longstanding concerns about air Funded by Perth & Kinross Council encourage active travel and improve connectivity. quality in Perth, by diverting traffic and the Scottish Government One team Using the ethos and approach of the Perth and Kinross away from the most congested and via Transport thecommunities CTLR to deliver Everyone involved in the project is part of one team.

Offer,Scotland, we will work with Client, contractor, consultants, subcontractors, education, cultural and environmental polluted parts of the city centre. project has been employment, heralded as suppliers: only by working collaboratively as one community benefits’ projects that will ensure a lasting playing a vital role in the future will we deliver the type of project everyone aspires to. social value for communities in the area.

The project also enables of Perth and Kinross – both new, planned and committed economically and environmentally.

Quality We will deliver the best quality project we can all be development as set out in the proud of at the best value. We strive to get things Local Development Plan, meeting Following a robust procurement right first time, deliver on budget and on time. the requirements of TAYplan and process, in August 2021 engineering unlocking the sustainable growth of and construction group BAM UK & the Perth area.

Ireland were awarded the contract for the detailed design and advance Ferguson Denise Ritchie Carol Geddes Gary Wilkie William Diver The CTLR project centres around works of theJillian project.

The second the construction of Destiny Bridge part of the contract for construction – a three-span bridge over the was awarded in September 2022.

“As a key element of the Perth Transport Futures infrastructure programme, the CTLR is hugely important to the future of Perth & Kinross.

It will undoubtedly transform travel across the region as well as reducing pollution in Perth city centre, and in turn, will unlock the economic potential of the area.”

John Swinney First Minister of Scotland

Design and Concept In 2017 Perth & Kinross Council appointed Sweco, one of Europe’s leading engineering, environment and regulatory consultancies, to design the preferred alignment of the new road linking the A9 north of Inveralmond to the A93 and then the A94 north of Scone.

This innovative approach to carbon savings has now been embedded in the British Standards Institution’s recently updated PAS 2080:2023 Carbon Management in Buildings and Infrastructure guideline document, as an example of best practice for procurement.

This included preparing the planning application and identifying key priorities around budget, added value and decarbonising the build through the initial design and procurement process.

In addition, engineers from both Perth & Kinross Council and Sweco were awarded the accolade of Institution of Civil Engineers (ICE) Carbon Champions.

Various concepts were proposed and discussed for the bridge itself, but it was the cost and carbon efficiencies in the chosen design that presented the most compelling case.

Making the Decision Cost and Construction Efficiencies As part of the design and planning process, Perth & Kinross Council decided on a three-span, low-level bridge with the western back span over the Perth to Inverness-Highland railway line.

Cost and environmental risks increase greatly when water-based construction is involved, but this design utilised piers outside the normal extents of the River Tay (except in the eastern floodplain), making it the most economical choice in terms of capital costs, as well as offering ease of construction, protection of the River Tay, and efficiencies for future maintenance.

RETAINING WALL

82000

150000

75000

RAILWAY

ACCESS TRACK

(APPROX. 1:200 YR FLOOD LEVEL) RIVER TAY

On contract award BAM UK & Ireland appointed design consultants Arup/Fairhurst (as a joint venture) to undertake the detailed design of the project, including Destiny Bridge.

Following consultation with statutory consultees and user groups, including Network Rail, SEPA and Tay District Salmon Fisheries Board, planning consent for the scheme was granted in October 2020.

“The main aim during the design, procurement and build process was to deliver the project as close to a net zero carbon development as possible, underscoring Perth’s intention to become one of the most sustainable small cities in Europe.”

Jillian Ferguson, Roads Infrastructure Manager, PKC

Design Engineering The Wider Scheme Arup Fairhust Joint Venture were responsible for value engineering, detailed design and construction supervision of the scheme on behalf of BAM UK and Ireland.

To accommodate the new Destiny Bridge the new Kingsway Road was designed to connect the A9, Stormontfield Road, A93 and A94. The design of this new section of road included a range of earthwork design techniques to prepare the ground; roadside drainage and basins; a new green bridge; culverts; traffic signs; safety barriers; street lighting and landscaping.

A 2km section of the existing A9 trunk road was realigned.

The delivery of this crucial part of the project infrastructure required a close working relationship between PKC, Transport Scotland, BAM and the design team to ensure the design met the requirement of all stakeholders and complied with standards.

Innovative 3-dimensional design methods were adopted from the start of the detailed design. This allowed the team to co-ordinate infrastructure components to ensure all the designed elements avoided construction clashes whilst on site. These models were used during the construction stage to achieve accurate positioning of vital components, generating construction efficiencies and improving delivery time.

Design Balanced Cantilever Challenges Destiny Bridge consists of a three-span post-tensioned concrete box girder deck supported on reinforced concrete abutments, piers and foundations. The deck sits on bearings which allow it to slide and rotate relative to a fixed point at the east pier where horizontal loads such as vehicle braking are resisted.

Post-tensioning is a technique used to achieve a stronger, more durable structure. A network of ducts are cast into each concrete segment through which high-strength steel tendons are then placed. Once the concrete has reached sufficient strength the tendons are tensioned using hydraulic jacks.

These tension forces pull the segments together, adding a compression to the concrete and enhancing its strength and stiffness. The internal stresses from the post-tensioning counteract the external stresses from loads, reducing structural deformation and concrete cracking. In addition to the tendons, the concrete is also reinforced with steel bars (reinforcement) which are not post-tensioned (stressed).

In order to allow construction over the Tay and the railway the bridge was built using the balanced cantilever method of construction with the deck built symmetrically and sequentially out from the piers. This method greatly influenced its design, with some of the most onerous load scenarios occurring during it. Segments were effectively hung together through the stressing of tendons located in the top slab of the box, known as cantilever tendons. In latter stages of construction tendons in the bottom slab of the box were tensioned, known as continuity tendons. These tendons help reduce deflections and cracking and improve the overall distribution of forces.

With hundreds of load scenarios to consider, a complex geometry and thousands of components to the bridge the engineers drew upon extensive use of coding, visual scripting and computer modelling to optimise the design. All tendons and reinforcing steel were modelled in 3d. This simulation approach reduced the risk of clashes between components and the potential for on-site changes during construction.

Challenges Resolved The Railway and Cofferdam A project of this size and scale is never without challenges, and for the Destiny Bridge build, one of the key considerations was the Perth to Inverness-Highland railway line that runs parallel to the River Tay. Looking forward, it is highly likely that this important network line will become electrified, necessitating a 6m clear height between bridge and line. Subsequently, this created a pinch point on the west side of the bridge.

Working in consultation with Network Rail throughout the initial and detailed design processes Sweco, BAM UK & Ireland and their designers Arup/Fairhurst adapted initial designs by lowering the east pier, and easing it into the existing land levels – this reduced material volumes and the carbon impact.

As a result the east pier moved closer to the water, which required an additional layer of construction in the shape of a cofferdam. The fabrication of this 16m x 16m boxlike structure is arrived at by driving 10m long steel sheets into the soil below water level and sealing them to allow a dry area for the piling and foundation work to take place.

~16m

Left: The Cofferdam Footprint Above: The railway line passes right under the bridge, and required 6m clearance

T he cofferdam

Piling Building a Strong Foundation As with many Scottish glens, the ground around the River Tay is made up largely of soft silts and clay. Unsuitable as a stable base for laying foundations, a process called piling takes place, which in the case of Destiny Bridge, saw engineers drill down to rock some 55m below ground level on both east and west sides.

Installing 25 piles at each pier, with each measuring 1.0m in diameter and between 50m and 55m in length, the piling process involved the placing of reinforcing steel and the pouring of concrete into the drilled holes. Separately, 20 piles were also drilled for the west abutment, and 15 piles were drilled for the east abutment. These measured 1.35m in diameter.

The concrete piles were then cut down to offer an even surface for the placement of a 2.5m thick reinforced concrete pile cap. Once complete, the piling process formed the base of the east and west piers of the bridge.

“Due to the complexity (diameter and depth) of the piles, we encountered significant challenges which resulted in piling operations taking longer than originally anticipated. This was overcome by procuring additional specialist equipment and extending working hours. In total, the critical piling operation for the pier foundations was completed in just under nine months.”

Derek Walsh Contracts Manager, BAM UK & Ireland

Substructure Forming the Basis of a Bridge The substructure of any bridge forms the all-important support for the main bridge superstructure. It is the connection between the superstructure (bridge deck) and the foundations that facilitates load transfer.

On Destiny Bridge, the substructure includes the east and west piers which sit on the banks of the river, and the east and west abutments, which sit further back on the approach to the bridge and transfer the weight of the structure into the foundations.

Made of reinforced concrete, the piers of Destiny Bridge are up to 8.9m high, and 6.3m wide, and the abutments are up to 16.4m high and 15.83m wide.

“Integral to the structure construction was the design, fabrication and installation of temporary props located at each pier which consist of heavy-duty steel circular hollow sections. They were installed as part of the sub-structure construction albeit only becoming operational once the deck segments were commenced.”

David Kilburn, Regional Engineering Manager BAM UK & Ireland

Hammerheads Building Out As the first section of the superstructure, the hammerheads are the all-important starting blocks of the bridge deck itself, and act as the centrepoint for the form traveller and deck segment construction. All bridges are designed to allow thermal movement to take place. This natural process occurs during temperature changes, when concrete is heated and expands or cooled and contracts.

To allow this to happen safely, bearings are installed on top of the piers and abutments with Teflon-like surfaces to allow the bridge to move freely around a fixed point which is the east pier south bearing. The bearings are also there to reduce the load effects into the piers.

During the construction process, the hammerhead allows the growing superstructure to move safely across the substructure and transmits the variable loads of the build into the piers. To support the out of balance forces, temporary props are used to stabilise the hammerhead and are removed only once the bridge is complete.

“Arguably, this element of the bridge construction was the most challenging, largely due to the severe weather encountered during construction of the hammerheads. The construction team endured flood events and freezing temperatures throughout the winter of 2023.

“The hammerheads’ formwork was temporarily supported to ensure the concrete elements gained sufficient strength to facilitate post tension stressing and removal of the temporary formwork supports. There was 890m3 and 162T of steel in each hammerhead which were up to 17.5m from ground level.”

Derek Walsh, Contracts Manager, BAM UK & Ireland

The Superstructure Takes Shape Form Traveller and Deck Segments

Made up of over 3,850 pieces, construction of the two Balanced Cantilever Form Travellers around the hammerhead denoted an important stage in the project – the commencement of the deck segment build for Destiny Bridge.

The construction of the 56 individual deck segments, which typically varied between 4.6m and 5.65m, and were fabricated from

reinforcement steel, high-strength concrete, and post-tensioning cables, followed a careful sequence, alternating between either side of each pier, to maintain a perfect balance.

During this process, both Balanced Cantilever Form Travellers moved along the superstructure, offering local people a striking, visual representation of the progress being made.

Each form traveller weighed approximately 123T and was supported by a superstructure frame located back on the bridge deck. During each deck segment concrete pour, an additional 195T of weight was supported by each form traveller.

Working with Experts Global and Local Knowledge Calling on global expertise, the form traveller system on Destiny Bridge was supplied by specialist Norwegian contractor, Strukturas, and construction of the main deck segments was carried out by Carrapatelo Construction Engineering Ltd from Portugal, who were supported by local resources to assist with the works.

In total over 5,000m3 of concrete was cast into the deck segment utilising close to 900T of steel reinforcement.

In addition, approximately 320T of stressing strand and 142,000kg of grout were used in the construction of the bridge which was supplied and incorporated into the bridge by stressing specialist, VSL. “The form traveller system is widely used in the construction of balanced cantilever structures throughout the Civil Engineering industry. Key to the success of their use is careful and methodical assembly and installation.

“Once in place, the use and operation of it is a repetitive process, with a typical segment construction cycle taking approximately one week. Having skilled and experienced specialists as part of the team was critical to the success of the project.”

Derek Walsh Contracts Manager, BAM UK & Ireland

Visualising the Scale Volume of concrete cast into the deck segment = 5 million litres, or 2 Olympic swimming pools!

The deck concrete alone used

There were

900 tonnes of steel reinforcement

142 tonnes of grout used in the bridge

= a family of 20 elephants!

Plus

320 tonnes of stressing strands

= the weight of 6 blue whales!

= 25 double decker buses!

Stitch Process | Tying the Superstructure Together As the final stage in the main superstructure build, the threestitch process on Destiny Bridge followed a precise construction sequence to ensure balance of load throughout the process.

The first stitch, segment EP-SS14, is located on the east end of the structure, and was poured on 23rd July 2024. Once complete, the east section of the structure was stressed using post-tensioning cables, before moving onto the internal kentledge (an in-situ block of concrete used as permanent ballast or counterweight).

This pour facilitated the installation of an alignment device at the bridge mid-span, ensuring both approach decks were at the same

level before completing the second stitch (WP-MS15) on 19th August 2024.

The third and final stitch, segment WP-SS15, located on the west end of the structure, followed a similar process in that the main deck continuity tendons were stressed; however, at this stage the western pier temporary prop was removed using hydraulic jacks before the alignment device was set in place.

The third stitch was poured on 16th September 2024, joining the bridge and heralding the completion of the superstructure’s main construction.

“The completion of the final stitch marked a significant milestone for the project which was testament to the hard work and dedication of the bridge construction team. By achieving this in September 2024 it ensured that the project would be completed for early spring 2025.”

Derek Walsh Contracts Manager, BAM UK & Ireland

Finishing Futureproofing the Infrastructure Once the main construction is complete, the finishing process can start. Although it looks to the untrained eye to be ready, an additional four-month period is required for the final works to take place.

The deck waterproofing defends against the Scottish weather and protects the structure from road salts, car fumes and other spillages.

Barriers come next, with two different types used. The N2 barriers run alongside the majority of the bridge, with H4A barriers allowing for higher protection above the Perth to Inverness-Highland railway line.

Kerb drainage units are installed next, which collect water from across the structure, and convey it to the lower, east side of the bridge and into the drainage network.

Finally, cycle paths, pavement, line marking and road studs are added to provide the last elements of Destiny Bridge.

“The completed bridge is a concrete box, with cantilever wings. Access through stairs and walkways at both east and west abutments, stretches through the entire length of the bridge to permit routine inspections of the internal structure, and to provide access to the bearings.”

Paul Johnston, Sweco

Environment and Ecology Greener Construction Immediately following award of the Detailed Design and Construction Contract, BAM UK & Ireland engaged with SEPA, NatureScot, Perth and Kinross (Planning) and other regulatory bodies to ensure the carbon efficiencies and ecological focus established at procurement stage would continue throughout the life of the project.

Initially, elements of the specimen design were revisited to realise value engineering opportunities wherever possible. Of note, the redesign of the spans and cross section of Destiny Bridge led to the elimination of in-river working at the west pier, and a reduction in construction materials required for the deck. Successful refinement of culverts was also achieved through this early consultation.

Construction of the east pier cofferdam and associated in-river works posed significant environmental risk and had to be undertaken outwith seasonal constraints in consideration of migrating fish. Sharing the construction programme and methods with SEPA was key in ensuring compliance with consents, as well as agreeing measures to prevent pollution.

Alongside this, ecological surveys were undertaken in advance of construction to establish the baseline for ecological diversity. This allowed BAM UK & Ireland to develop live constraint maps and to identify any additional consent required. Continuous liaison with SEPA, NatureScot and others, ensured development of species protection plans in accordance with current guidelines.

“During the project build, an independent site Environmental and Ecological Clerk of Works (ECoW) was engaged to report to PKC as both the client and the planning authority. BAM also employed a second onsite ECoW, who was supported by an Environmental Manager to ensure construction progressed in accordance with all consents. Regular interface meetings with key regulatory bodies yielded a positive culture and allowed for ongoing advice and collaboration.”

John Slaven Senior Project Manager, BAM UK & Ireland

Visualising the Scale

The Piers Volume of concrete in both piers:

=1,150m

3

The Pile Caps

The Abutments

were constructed using over

Over 1,425m of concrete was used to complete both sides

260 tonnes of steel

That’s enough concrete to fill

A similar volume of water flows under the bridge every 5 seconds

McDiarmid Park knee high!

= the weight of a herd of 40 elephants

Total span of 307m

3

+205 tonnes of steel reinforcement = the weight of a large blue whale

longer than 6 Olympic swimming pools!

The Green Bridge The Green Bridge at Highfield, which forms part of the overall scheme, is an outstanding example of this type of structure.

Careful consideration during the design process was given to ensuring the structure blended into the surrounding beautiful landscape, whilst also serving its function to provide connectivity for people and animals and enhancing biodiversity. The mural and the living bench were undertaken

by Scottish artists as part of the Community Artwork project for the whole scheme.

“This structure required careful design considerations. The foundations had to be designed to accommodate large forces caused by the low slender profile of the arch. The buried nature of the structure also allowed the landscape design to traverse the road below, creating a fantastic ecological corridor and an asset for the local communities.”

Carol Geddes Project Manager, Arup Fairhurst Joint Venture

The Wetlands An important feature on the New Kingsway route is the new wetlands area which is located slightly west of Stormontfield roundabout. The combined cycleway and walkway route meanders to the south of the wetlands allowing the public to experience nature up close.

The primary functions of the wetlands are to provide a habitat for wildlife while also containing and treating surface water from the new road infrastructure.

The addition of a bird hide gives birdwatching enthusiasts a good vantage point and shelter during unseasonal weather. Aquatic plants and shallow pools enhance the wetlands and attract other wildlife species to the area also.

“It was important for Perth & Kinross Council to involve the community in the project where possible. One example of this was giving local children the opportunity to work with artists engaged on the project to design and create legacy artwork pieces for people to enjoy.”

Sarah Gardner Project Officer, Perth & Kinross Council