A scathing report on a $38 million walkway built in Sydney's Moore Park states the bridge was never justified and should not have been built so quickly.

The Albert 'Tibby' Cotter Walkway crosses over Anzac Parade in Moore Park.

Former premier Barry O'Farrell wanted it built in time for the 2015 Cricket World Cup at the Sydney Cricket Ground in February.

The acting auditor-general Tony Whitfield found the tight deadline "added substantially to the total cost of the walkway, which is projected to be $38 million".

Mr Whitfield said the project should have taken 20 months but instead was completed in 14 months.

"The deadline not only led to an expensive alliance arrangement, but to RMS (Roads and Maritime Services) developing an additional design as a risk mitigation strategy, additional overtime, inefficient use of equipment and temporary works," the independent report said.

"It also prevented concurrent delivery with the CBD and South East Light Rail project, which RMS thought would save millions of dollars."

Mr Whitfield went further, stating that both Transport for NSW and RMS "could not provide evidence of a compelling economic or financial argument to support the construction of the walkway".

He made recommendations for Transport for NSW and for RMS, saying that for future projects, both agencies needed to prepare a business case that adequately justified the project and analysed the costs and benefits of any unusually tight deadline.

Labor claims Baird should share blame

Greens MP Mehreen Faruqi said the bridge was a dud.

"This is a bridge that no-one actually wanted and hardly anyone uses," Ms Faruqi said.

"The Government did know that the World Cup was happening in 2015 four years ago, so they could have planned well for a bridge that was in the right place and not rushed through a botched job that cost the taxpayers $38 million."

Opposition infrastructure spokesman Ryan Park said although Mr O'Farrell signed off on the project, his replacement, Mike Baird, should share some of the blame.

"The Premier sat around the Cabinet table, he was the Treasurer at the time," Mr Park said.

"This is a Government that needs to be focusing on a lot more when it comes to delivering important projects for the city.

"We don't have $38 million to be wasted on projects that don't stack up."

Minister defends walkways, hoses down report

Roads Minister Duncan Gay defended the walkway when asked about it in Parliament this afternoon.

"We said we'd have the Albert 'Tibby' Cotter Walkway open for the Cricket World Cup where the eyes of the world were on Sydney and we achieved it," he said.

"A recent RMS survey indicated more than 6,000 people used the bridge over a six-day period with no major events, so [that is] an average of more than 1,000 users a day.

"Also since it opened more than 38,000 people have used it during major events."

Mr Gay downplayed the acting auditor-general's report.

"For all the noise from the Greens and the Heritage Council, what have they got — three straightforward administrative recommendations," he said.

"They worked hard on this report and this is all they've come up with. The first two recommendations relate to project analysis and assurance were already accepted as part of an earlier audit in May this year."

But the Minister said he disagreed with some aspects of the report.

"Roads and Maritime does not agree the increased cost can be attributed to the deadline," Mr Gay said.

"The deadline was achievable within the original budget.

"An independent project consultant report completed by TBH confirmed that external delays and scope changes imposed by the Heritage Council increased costs by $10.6 million."