The Mitcham Hills T-junction where James Road meets Old Belair Road was in May 2019 earmarked for a $20m federally-funded upgrade to transform it into a single-lane roundabout with a bypass lane for city-bound traffic.

Old Belair Road is the most direct route to the Adelaide CBD from Belair, while James Road feeds traffic into it from Hawthorndene, Glenalta and the Upper Sturt area.

At morning peak hour, traffic often banks up on James Road as commuters struggle to turn right at the unsignalled T-junction due to the volume of city-bound traffic on Old Belair Road.

The intersection of James Road and Old Belair Road was earmarked for a $20 million upgrade to become a single-lane roundabout with a northern bypass lane. Left photo: Greg O’Grady; right photo: Department of Infrastructure and Transport.

Around 17,500 cars pass through the intersection each day, according to a Department of Infrastructure and Transport study from September 2019.

Construction on the new roundabout was scheduled to commence in late 2021 but that was pushed back twice after the design faced significant community backlash and repeated calls for suspension.

Local residents’ groups and Mitcham Council were concerned about the proposed felling of 148 native trees and whether the roundabout was the best solution for the area’s peak hour traffic problem.

Native trees lining the James Road/Old Belair Road intersection. Photo: Pete Gehlert

The Malinauskas Government put the project on hold in April 2022 and referred it to the state government’s independent infrastructure assessment agency, Infrastructure SA.

Infrastructure SA’s final report was published today, with the agency finding the project is “not justified” and had a rapid benefit cost ratio (BCR) of 0.9. Any BCR score below 1 means the costs outweigh the benefits.

“Ultimately, the proposed junction treatment represents a capital expenditure of over $15 million to address traffic issues primarily caused by 240 vehicles per hour in the morning peak hour(s),” Infrastructure SA found.

“The proposed roundabout will also result in the potential loss of 148 native trees, which have unique environmental value and are of significant interest to the community.

“Based on the design of the current roundabout solution and the associated impacts, both in terms of costs, benefits and disbenefits and the possibility of other non-infrastructure and infrastructure options that could minimise impacts and traffic issues at this junction, this Review finds the investment as currently proposed is not justified and further options to potentially reduce demand at the junction should be explored.”

Artist impression released in February 2021 of the Old Belair Road/James Road upgrade. Photo: Department of Infrastructure and Transport

Infrastructure SA was also critical of the Department for adopting a “one size fits all approach” to defining the objectives of the Old Belair Rd upgrade.

The report found that improved safety and traffic efficiency accounted for 75 per cent of the project weighting, compared to just 5.7 per cent for environmental impacts.

“The development of options and subsequent shortlisting of options appears to have placed minimal value on environmental impacts,” Infrastructure SA found.

“As a result, all shortlisted options generated similar junction footprints, resulting in similar environmental impacts to the site.

“There was no documented evidence to suggest work was undertaken to reduce or mitigate environmental impacts of options during the options development phase.”

In its list of recommendations, Infrastructure SA said: “Project teams should have stronger regard for stakeholder views and environmental impacts during option development processes.”

The agency recommended the government suspend the project and review nearby intersection upgrades to explore ways to reduce traffic demand on the junction.

It also recommended improving access to public transport in the Mitcham Hills area to get more cars off the road.

Transport Minister Tom Koutsantonis today confirmed the state government would not be proceedings with the project.

“We undertook that if elected we would pause this project pending an independent review, and that review has now vindicated that approach,” he said in a statement.

“This was always the wrong priority and it will not be proceeding.

“We are listening to the community and acting on the independent advice provided by Infrastructure SA.”

Koutsantonis’ office said other upgrades in the area – including an upgrade of Shepherds Hill Road, Brighton Parade and Waite Street intersection and the Russell Street, Main Road and Sheoak Road junction – will go ahead as planned via existing state government funding allocations.