The Stirling Interchange is located on the South Eastern Freeway in South Australia, approximately 16 km from Adelaide’s CBD. The freeway is critical to South Australia’s economy, as it is the primary access road to the eastern and southern South Australia and to Victoria. Interstate freight movements delivering around 30,000 tonnes per day, representing around half the State’s interstate goods transport.
The Stirling drainage culvert comprised 442 m of twin 1500 mm diameter corrugated steel drainage pipes following the original creek alignment up to 11 metres under the Stirling Interchange. In 1984, a 6 m deep section of the culvert collapsed, causing the partial collapse of the roadway and edge of the South Eastern Freeway. Despite repairs, ongoing deterioration of the steel pipes raised ongoing concerns about safety.