Multiple design ‘failures’ led to crumbling South Rd overpass
UPDATED: A pedestrian and cycling overpass closed after dropping debris onto South Road was not built according to Australian design standards, a report to the State Government has found.
Transport and Infrastructure Minister Stephen Mullighan.
A report by engineering company Aurecon ordered by the Government found that three aspects of the design of the shared cycling/pedestrian path attached to a tram overpass at Glandore contravened Australian design standards.
South Road was closed for four days last month, after a cyclist reported that parts of the bridge had fallen onto the road below. The State Government not only closed the bridge, but ordered an audit of all 1500 road and rail bridges under its control.
Transport Minister Stephen Mullighan said today the Aurecon report found the cause of the problem was a design failure, raising serious questions about how the bridge could have been designed in breach of Australian Standards and also passed independent certification.
“This is unacceptable from a series of companies who are very experienced nationally and internationally in delivering infrastructure projects,” he said.
He said there were several design problems: the “unusual” use of a single T-section concrete girder (instead of two); the heavy weight of “anti-throw screens”, which prevent people throwing objects on the road below; southerly winds catching these screens and placing more stress on the structure.
Together, these effects meant the structure moved out of its designed position.
The report found other parts of the pedestrian and cycling path were showing signs of this phenomenon, including “deformation, girder rotation and cracking of the keeper walls”.
The report said there was no concern about the adjacent tram bridge.
Work will begin immediately to fix the problem on the bridge, which was designed for McConnell Dowell by engineering firm AECOM and certified by Wallbridge and Gilbert Consulting and Engineers.
Design flaw blamed for South Rd overpass woes, expect traffic delays during night works to remove screens #Adelaide https://t.co/t7mYeyNb7u pic.twitter.com/1KISuTSUXK
— ABC Adelaide (@abcadelaide) February 20, 2017
Mullighan said the report had been provided to the consortium who designed and built the path.
He said his department and Government lawyers would be having “robust” discussions with the consortium to make sure they met the costs of fixing the problem, plus the costs already incurred so far.
In a statement released this afternoon, McConnell Dowell said it was reviewing Aurecon’s report.
“As long-standing, well-regarded companies with a strong track record in designing and constructing major infrastructure projects in South Australia, we regard the movement experienced with the shared path bridge as a matter of significant concern,” the company said.
“We are committed to continuing to work with the Department of Planning, Transport and Infrastructure to find a safe, permanent solution.”
Work started today to remove the anti-throw screens, as well as implement Aurecon’s recommendations to bring the cycling and pedestrian path back to full working order.
During day works, South Road will remain open in both directions at all times, with access retained to businesses and other properties.
The minister promised that any works which required lane closures or through traffic to be held up would occur at night. Traffic could be disrupted for up to 15 minutes on as many as nine occasions during night works, which will occur between 9pm to 6am later in the week.
