Hazard protection on the Southern Expressway Duplication

The Southern Expressway is an 18.5 kilometre carriageway connecting Adelaide’s Main South Road at Darlington with Main South Road at Old Noarlunga.

Before the project, it provided for travel in one direction only. On weekdays, traffic flows north from two o’clock in the morning to 12.30 in the afternoon, and south from two o’clock in the afternoon to 12:30 in the morning.

During the 90 minute changeover period, access to the road is progressively closed and re-opened to traffic. On weekends and public holidays, the times for northbound
and southbound traffic flows are reversed. This was the world’s longest reversible one way freeway.

The Southern Expressway Duplication project has transformed the reversible expressway into a conventional two-way expressway opened to two-way traffic on 3 August 2014. The duplication was built entirely on the western side of the original roadway, with three lanes from Darlington to Reynella and two lanes from Reynella and Old Noarlunga.

The project also widened the existing expressway bridges over local roads, lengthened pedestrian and road bridges over the Southern Expressway, and added new on-ramps and off-ramps at existing interchanges.

Design of the project coincided with the introduction of the Ezy-Guard Smart system into the Australian safety barrier market. Due to its proven high-performance characteristics, this MASH Test Level 3 system was chosen to mitigate many of the associated safety hazards from such a busy freeway.

Installations included median and verge applications to prevent run-off-road vehicles from impacting rigid roadside hazards or entering non-recoverable embankments.

These verge installations typically used the energy-absorbing ET2000 Plus or MELT end treatments.

Installation was carried out by SA Guardrail Pty. Ltd., one of the leading dedicated installers of road safety barriers in South Australia.