Southern Expressway duplication

Southern Expressway Duplication Project, undertaken by the South Australia’s Department of Transport and Infrastructure (DPTI), involved duplication of the existing Southern Expressway in Adelaide into a two-way expressway. Construction work on the project commenced in early 2012 and the expressway was opened in August 2014.

Prior to duplication, the expressway had exclusively facilitated a reversible one-way traffic movement stretching from Darlington to Nourlunga. The duplication project converted the one-way road into a two-way expressway.

The total project investment was estimated at $407.5m, which was funded by the South Australian State Government, and created approximately 500 jobs.

Construction history of the existing Southern Expressway

“The duplication project converted the one-way road into a two-way expressway.”

Construction of the expressway, which began in July 1995 and was completed in September 2001, was undertaken in two stages – the routes from Darlington to Reynella and from Reynella to old Nourlunga.

The first stage was completed in 1997 and the second in 2001. The expressway is 21km long, including the distance from the Main South Road to Marrion Road, which was upgraded between 1987 and 1994.

Purpose of duplicating the Southern Expressway

The duplication to a two-lane road makes the expressway a better alternative for motorists and reduce travel times by 13 minutes when compared with taking the Main South Road, which consists of 16 signalised intersections. The new road operates 24 hours a day, up from the previous 22.5 hours.

The project also provides good access for commercial operations in strategic areas such as Reynella, Lonsdale and Noarlunga, and has opened up access to tourist destinations on the Fleurieu Peninsula.

Southern Expressway duplication project details

The new two-way expressway was built on the western side of the existing road. The total length of the duplicated expressway is 18.5km, stretching from Darlington to Old Noarlunga.

The project included the extension and duplication of bridges, pedestrian walkways and interchanges located along the existing expressway, as well as construction of new ramps.

The expressway section from Darlington to Reynella is provided with four traffic lanes heading northwards, while the stretch between Reyneylla and Old Noarlunga consists of two lanes.

For the southwards traffic, the new expressway facilitates three lanes from Bedfork Park to Renella, and two lanes from Reynella to Old Noarlunga.

A total of 17 bridges, walkways and cycleways were duplicated or extended. The project also aligned the 300m-long Field River and Trott Park Creek section as well as the 200m-long Field River section near Young Street Bridge.

Landscaping was done at various locations affected by the construction work.

Construction details of the expressway duplication

“The total project investment is estimated at $407.5m.”

The design of the new expressway and the progress of the construction work were constantly improvised. The project saw the excavation of 220,000t of asphalt pavement and approximately two million tonnes of soil and rock.

Excavation work was carried out by using a D11 bulldozer and the soil was transported by huge trucks. With a capacity of approximately 1,000HP, the dozer weighs roughly 105t. Certain locations along the expressway were cleared by blasting.

Key players involved with the expressway duplication project in Adelaide

The contract for the design and construction of the project was awarded to the 50/50 joint venture of Baulderstone and Abigroup (BAJV). The two contractors form part of Land Lease Group. BAJV was also responsible for drafting the contractor’s environmental management plan (CEMP) for the project.

Parsons Brinckenhoff, along with Wallbridge and Gilbert, were responsible for assisting DPTI in preparing the alignment of the expressway and studying various environmental, economic and social issues connected with the project.