Liverpool City Council has come under fire after confirming it spent nearly $140,000 on the installation and swift removal of a controversial roundabout in Austral in western Sydney that baffled motorists and went viral worldwide.

Nicknamed the “Diamondabout”, the oddly shaped intersection at Twenty Eighth Avenue and Fifteenth Avenue opened on June 20, only to be painted over less than a week later. Confused drivers were caught on aerial footage performing awkward manoeuvres, with one car seen in aerial footage performing a three-point turn to clear the sharp corners.

Council documents reveal the roundabout had originally been intended as an oval design, but amendments between Transport for NSW, council’s design team and its traffic committee saw a non-standard diamond layout approved in February, reports the Sydney Morning Herald. Officials were warned about potential compliance issues as early as October last year, but the final plans still went ahead.

The project cost $92,885 to build, followed by a further $53,914 to remove and remediate the site, bringing the total spend to $139,937. Give-way signs have since replaced the markings.

The location of the infamous roundabout before it was installed (via Google Maps)

The diamond roundabout was one of six traffic-calming devices installed in Austral after residents petitioned for safety improvements to the congested Fifteenth Avenue corridor, a key route earmarked for major upgrades ahead of the opening of Western Sydney Airport. Both Prime Minister Anthony Albanese and NSW Premier Chris Minns have pledged $1 billion to transform the road into a state-owned transit corridor.

Councillor Peter Ristevski, a vocal critic of the project, said the fiasco had embarrassed not just Liverpool but Sydney as a whole. “This episode went viral globally and has left the council looking like an international laughing stock,” he said. “The waste of ratepayers’ money is unforgivable.”

Council has promised lessons have been learned. A spokesperson said the matter has been fully investigated and findings will be tabled at Wednesday’s council meeting. “The lessons are already shaping improvements to how we plan and deliver future traffic projects,” they said.

The embarrassment comes as Liverpool Council is already under scrutiny, with the NSW Office of Local Government conducting an inquiry into allegations of dysfunction, maladministration and mishandling of state grants.