A major upgrade of Commonwealth Avenue bridge is one step closer, after the $124 million project was declared an infrastructure priority in Australia's COVID-19 economic recovery.
Infrastructure Australia's decision confirmed the 57-year-old bridge would be strengthened and upgraded rather than knocked-down and replaced, a move foreshadowed by the National Capital Authority earlier this year.
The federal government advisory body on Tuesday announced it had added the proposed bridge upgrade to a list of "nationally significant" projects to help lift Australia out of the coronavirus-induced economic recession.
While the decision does not mean the project has been approved, it does put it in the frame for funding ahead of next month's federal budget.
The upgrade, which would be entirely federally-funded, would involve work to strengthen the iconic bridge and widen the traffic lanes and pedestrian paths.
Infrastructure Australia chief executive Romilly Madew said the upgrade would extend the lifespan of the bridge by 50 years, while helping to reduce travel times for motorists and improve safety for cyclists and pedestrians.
The advisory body agreed the project was worthy of addition to the priority list after it reviewed a business case submitted by the National Capital Authority.
Infrastructure Australia's evaluation, conducted earlier this month and published on Tuesday, found the project had a "strong strategic and economic case" and would deliver a "net benefit to the economy".
The report found the bridge had reached its traffic-carrying capacity more than three years ago, and problems would worsen under the weight of Canberra's growing population.
A number of features of the 310-metre-long bridge also failed to meet minimum safety standards, including safety barriers, travel lane widths, shared paths and accessibility approaches.
While the advisory body concluded the project had merit, it believed the National Capital Authority - a Commonwealth agency - had "overstated" its benefits in the business case.
According to the evaluation report, the business case worked on the assumption that if the upgrade did not proceed, two of the bridge's six lanes would have to be closed and heavy vehicles diverted to ease pressure on the ageing structure.
Infrastructure Australia did not agree that such a drastic measure was necessary to keep the bridge safe.
The report showed the business case assessed eight options to address the problem, including the prospect of replacing Commonwealth Avenue bridge.
The potential cost of that option wasn't included in the evaluation, although the report said it would not have achieved a cost-benefit ratio greater than one.
In May, National Capital Authority chief executive Sally Barnes all but ruled a line through the option of a new bridge when she declared it was "probably off the cards".
The decision to upgrade, rather than rebuild, Commonwealth Avenue bridge would provide a clearer path to extend light rail over Lake Burley Griffin en route to Woden, as proposed by the Barr government.
The ACT government's long-held plan to build a third bridge between existing structures to carry light rail was thrown into some doubt when Ms Barnes last year flagged the possibility of replacing Commonwealth Avenue bridge.
According to Infrastructure Australia's report, the National Capital Authority intends to finish the bridge upgrades before the ACT government starts works so it could "avoid site conflicts".
The $124.9 million bridge upgrade would start next year and be completed in 2024, according to an indicative time frame set out in the evaluation report.
The advisory body strongly recommended that ACT and Commonwealth agency work together to coordinate the planning and delivery of their respective projects.
The Canberra Times asked the office of Treasurer Josh Frydenberg if funding for the Commonwealth Avenue bridge upgrade would be included in next month's budget.
In response, a government spokesman simply said: "The budget will be delivered on October 6."