ROAD TO 78KM NORTH SOUTH CORRIDOR: PAVED BY INNOVATIVE SOLUTIONS

Submitted by Department for Infrastructure and Transport

The North-South Corridor is one of the most ambitious, forward-thinking road infrastructure initiatives ever undertaken in South Australia.

The corridor is being progressively completed, piece by piece, by a succession of major infrastructure projects which have each left their own built legacy to the South Australian community. But as construction has progressed, the various component projects have developed different innovative solutions in response to construction complexities and evolving community expectations.

PLANNING AND DELIVERING THE CORRIDOR

Plans to build an efficient road transport route connecting the north of Adelaide with the south of Adelaide have been floated since the Metropolitan Adelaide Transport Study, released in 1968, proposed a “North-South Freeway”. However, the current iteration of the North-South Corridor – a 78km, traffic light-free motorway between Gawler and Old Noarlunga – was first identified in the South Australian Planning Strategy and other associated State Government strategic policies in the 2000s. These documents set out the vision for the North-South Corridor to be the major route for north- and south- bound traffic, including freight vehicles, running between Gawler and Old Noarlunga. The majority of the North-South Corridor has now been completed, thanks to the delivery of a number of major infrastructure projects focused on constructing individual sections of the corridor. Almost $5 billion of combined investment (in nominal terms) has gone into delivering these completed projects, with the Australian and South Australian governments working together to jointly fund the majority of these and the South Australian Government fully funding others. Each of the North-South Corridor projects has faced its own engineering and project management challenges and complexities, given the different urban development, land management requirements and existing road and services infrastructure along the corridor. For example, the Northern Expressway was, at 23km in length, the largest road construction project undertaken in the state since the 1960s at the time of its construction, while the Regency Road to Pym Street (R2P) Project contributed 1.8km of non-stop roadway but in a highly-developed and complex urban environment.

The community and government’s expectations of how major infrastructure projects should be built, in terms of which materials to use or how to support local motorists, residents and businesses, has also continued to evolve over time. As a result, each project developed different and often innovative solutions to adapt to these challenges.

DARLINGTON – BRIDGE LIFT OVER A MAJOR ROAD CORRIDOR

The Darlington Upgrade Project involved the design and construction of approximately 3.3km of upgrades to Main South Road, including a nonstop motorway between the Southern Expressway and north of Tonsley Boulevard and the construction of eight bridges, resulting in the removal of five sets of traffic lights. The project was delivered by Gateway South, a joint venture between Laing O’Rourke and Fulton Hogan, with design undertaken by Jacobs Group, Kellogg Brown & Root and SMEC Australia.

Gateway South realised from the outset that adopting a traditional bridge construction method for three of the eight structures would result in significant traffic and community impacts, given the complexity and size of the intersections involved: the Southern Expressway/Main South Road and Ayliffes Road/South Road/Shepherds Hill Road intersections. To keep disruptions to a minimum for the many tens of thousands of vehicles which travel through Main South Road every day, the project did something that had never been done before

This map shows the major completed sections of the 78km North-South Corridor to date, with the Torrens to Darlington section (between Tonsley and Hindmarsh) currently in the planning phase.

The 15.5km, three-lane Northern Connector is South Australia's first ever major concrete road.

in South Australia and, for a civil construction project of its scale, the whole of Australia.

The three three-span bridges, weighing between 3,000 and 3,200 tonnes and varying in length between 180 and 197m, were constructed ‘off-site’ and then transported into position and manoeuvred into place using ‘selfpropelled modular transporters’ (SPMTs). By designing, constructing and installing the bridges in this innovative way, rather than traditional methods, the number of weekend road closures that were required was reduced from at least seven per structure, to one single closure per bridge. It also provided additional employment opportunities for South Australians, with Bowhill Engineering undertaking the work to fabricate the bridge segments at its workshop. This type of bridge installation had, prior to the start of the project, commonly been used in Europe and America, however only for single-span bridges between 500 and 1,000 tonnes in weight and two-span structures with an average weight of 2,000 tonnes. For three-span structures, methodologies trialled at that point in time accounted for steel bridge components only and weights significantly less than 3,000 tonnes. Further, previous full bridge installations around the world using SPMTs had been on flat ground with the structure moving only a short distance. The Darlington Upgrade Project structures, in contrast, were constructed with steel girders, concrete deck and parapets already in place, before being transported along the existing road network over a distance of approximately 400m per bridge, with significant differences in gradients along the travel path. As a result of the unprecedented complexity of the activity, the project team was required to develop innovative methods to pre-wire the structure before transporting it, in order to monitor any changes in stress or strain, in real time, through its movements. The project generated new knowledge in relation to this method of three-span bridge construction and transportation, and it has since been repeated on other South Australian infrastructure projects, such as the Regency Road to Pym Street (R2P) and Ovingham Level Crossing Removal projects.

R2P – THINKING OUTSIDE THE BOX

The R2P Project involved constructing 100 per cent recycled material was used for the R2P Hudson Avenue site 1.8km of new office car park. non-stop roadway (three lanes in each direction) and a surface road (two lanes in each direction) and grade-separating the intersection of South Road and Regency Road. To do this, the R2P Alliance – a consortium of McConnell Dowell Constructors (Aust) Pty Ltd, Mott MacDonald Australia Pty Ltd and Arup Group Pty Ltd – considered a number of alternative approaches to deliver improved outcomes. For example, rather than encouraging vehicles to avoid using South Road and seek alternative routes during construction, the R2P Alliance implemented a staged removal of right turn movements at the South Road and Regency Road intersection, and provision of alternative routes, to increase the through-capacity of the busy intersection. To improve engagement with the various local businesses adjacent the roadway and support ongoing trade and access during construction, the R2P Alliance trialled the use of an Australian-first smartphone app which allowed for quick and easy communication with local businesses and residents for the first time in Australia. The SitePodium app enabled local businesses and residents to regularly engage with the R2P Alliance on areas of interest. The R2P Project also had a key focus on minimisation of materials and the reuse of existing materials on site, resulting in it becoming the first project in Australasia to obtain a certified Infrastructure Sustainability Council of Australia V2.0 Design Rating. The project sealed the construction office car park with 100 per cent recycled materials, allowing it to save 9.4 tonnes of carbon dioxide. It also worked to reduce greenhouse gas emissions throughout the project’s construction, through measures such as installing lower wattage lighting, using GreenPower at its project site compound and using lower emissions materials such as recycled asphalt pavement, reduced Portland cement concrete and recycled materials in kerbing. Measures such as these are expected to become more commonplace in the future, as the South Australian Government commits to net zero emissions by 2050 and looks to shift the infrastructure sector towards low-carbon materials and construction practices. NORTHERN CONNECTOR – GIVING BACK TO SA Supporting local industry, businesses and creating jobs were key focuses in the delivery of the Northern Connector Project. The project, delivered by Lendlease, involved constructing a completely new six-lane, 15.5km motorway providing a vital freight and commuter link between the Northern Expressway, South Road Superway and Port River Expressway. As part of the Industry Participation Strategy, the project was set a challenge to achieve over 90 per cent investment back into the South Australian economy. To this end, the Northern Connector was designed and constructed to be the first major concrete road in South Australia.

One of the pre-constructed bridge spans for the Darlington Upgrade Project being transported onto site by a self-propelled modular transporter in 2017.

The resultant use of concrete and steel enabled local companies to be engaged to maximise reinvestment back into South Australia.

Adelaide Brighton and Southern Quarries and Direct Mix provided the materials required for the 175,000 cubic metres of concrete that was used for the new pavement of the motorway. The project set a target to use 6,500 tonnes of Whyalla Steel, through InfraBuild (formerly OneSteel) to maximise local investment in the state. In late 2019, the target was surpassed with a total of 6,750 tonnes of steel used on the project. The project was also proudly supported by local Industry Partners Catcon and LR&M Constructions, which played a key role in delivering three of the major interchanges and sections of the motorway including earthworks, drainage and bridge structures. Additionally, Lendlease established NorthHub, an employment, skills and training centre to help northern jobseekers secure some of the 480 jobs a year on average on the project, particularly displaced automotive workers.

The project reached a total of 91 per cent reinvestment (almost $400 million) back into South Australia, delivering not only value for money, but strong investment and support for the State and local businesses.

T2D – THE FUTURE OF THE NORTH-SOUTH CORRIDOR

The 10.5km Torrens to Darlington (T2D) Project is the final piece of the NorthSouth Corridor, the most significant infrastructure project ever undertaken in South Australia.

The project is set to bypass 21 sets of traffic lights between the River Torrens and Darlington, and has been modelled to use a combination of twin threelane tunnels, lowered and ground-level motorways, as well as overpasses and underpasses at key intersections. In continuing the state-of-the-art practices used on the North-South Corridor to date, both the Southern Tunnels and Northern Tunnels are planned to be constructed using tunnelboring machines (TBMs). TBMs planned to be used will be approximately 100m long and will excavate tunnels 15m in diameter, progressing about 8-10m per day. In response to community feedback on the T2D Reference Design released in November 2021, the Department for Infrastructure and Transport is reviewing the planning work to date on the project. This is to ensure the design meets the highest standards and can generate the promised long-term economic, social, transport and environmental benefits.

Creating a pipeline of skilled workers for the Civil Construction Industry.

CITB will fund eligible employers up to $2,500 per school-based apprentice/trainee:

• $1,250 after completion of probation • $1,250 after SACE completion

For additional information, visit: citb.org.au/sbats

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