Majors Road Interchange

#Infrastructure

Addressing Traffic Demands:

A smoother journey and reduced travel times – the new Majors Road Interchange will make this a reality for Adelaide’s southern suburb commuters.

Majors Road is a vital connecting road, which currently has no access to the Southern Expressway, an urban freeway that links Adelaide with the Southern suburbs of South Australia. Currently, 13,200 vehicles use Majors Road daily, while the Southern Expressway sees a vehicle volume of nearly 6 times more.

The $120 million initiative is jointly funded by the Australian and South Australian Governments and commissioned by South Australia’s Department for Infrastructure and Transport. WGA was selected as the lead designer to support the project by Acciona Construction Australia, who are the lead Contractor for the project.

Our design work spanned across road alignment, drainage, pavements, earthworks, utilities, bridge structures, barriers, ITS Structures, traffic modelling, traffic signals, road lighting and temporary works.

A Collaborative Approach to Design and Construction

WGA’s work as the lead designer was instrumental in creating a successful and effective interchange arrangement. Blending technology with smart design, our work leveraged digital engineering tools such as 12d, AutoCAD, Revit, DRAINS, and Aimsun to optimise the project and reveal a design with innovative features. These digital tools allowed us to produce a fully federated Navisworks model of the project ensuring a fully integrated design solution. The new enhancements included:

Among the key innovations, our alternative Veloway alignment stood out by eliminating an underpass crossing and significantly shortening the southbound entry and exit ramps. This modification significantly reduced the amount of earthworks, retaining walls and pavements.

Expanded roads

On and off-ramps will feed vehicles to the Southern Expressway at Majors Road. The new northbound entry ramp includes ramp metering, a first for South Australia, which will assist traffic flow, minimising delays on the Expressway due to the merging traffic. The Majors Road bridge will also widen to accommodate six lanes, providing two through lanes in each direction to improve traffic flow.

Safety improvements

Patrick Jonker Veloway (a bikeway that runs alongside the Southern Expressway) will realign under Majors Road with better sightlines and improved orientation, offering cyclists a safer ride.
The additional traffic signals at the Majors and Adams Road junction will offer new and easy access to the recreation facilities in the area.
Emergency Services (Metropolitan Fire Services and Ambulance services) will have direct access to the expressway.
Power lines will move underground to enhance the area’s visual appeal and reduce potential disruptions.

Landscape boost

A shared-use path will be introduced with extensive tree planting to provide shade and improve the overall look of the area. Other proposed treatments include new pavement construction, LED Road lighting and new drainage for the extent of work.

The design placed a special focus on protecting the environment with careful planning, minimising the impact on Glenthorne National Park – Ityamaiitpinna Yarta, with no impact on Glenthorne Farm or O’Halloran Hill Recreation Park.

The project is considered a well-thought-out fix to help manage the increasing travel demands of the Southern Expressway. Moreover, the enhancements are expected to improve safety and connectivity that fuels economic growth by improving access to key surrounding recreational and tourism hot spots like the Glenthorne National Park, the Sam Willoughby International BMX Facility, the Southern Soccer Facility, and the beautiful Fleurieu Peninsula.

Image Credit: The Department for Infrastructure and Transport – South Australia