Sydney residents will have to contend with a "permanent congestion nightmare" caused by the already heavily delayed light rail project, the NSW opposition claims.
Labor leader Luke Foley on Wednesday hit out at the $2.1 billion project, labelling it "a dud" and predicting the government will not want to open it before the March 2019 state election.
"If they do, people will see how truly bad it is," he told reporters in Sydney.
The project represented an unenviable trifecta, Mr Foley said, because it was late, over budget and would deliver congestion problems.
It comes after an internal report highlighted the need for 67-metre-long light rail carriages along the CBD-southeast Sydney route to be granted priority over motorists.
The analysis, completed by GTA Consultants in late 2016, warned that light-rail commuters could face waits of up to nine minutes in total due to the carriages waiting at red lights, Fairfax reported.
"This is going to deliver a permanent congestion nightmare in the Sydney CBD," Mr Foley said.
Transport for NSW said the traffic report was based on a model developed in 2013 and did not reflect the current network and traffic volume.
Intersection-detailed designs, traffic signal plans and speed zoning were still being finalised, a spokesman said.
"We need to balance the needs of the new light rail with existing road users, and ongoing traffic modelling will ensure that we get that balance right, taking into consideration the current network demands," Transport for NSW said in a statement to AAP.
Planning documents estimate the end-to-end journey time to be 34 to 38 minutes.
The project's timeline for completion also came under heavy scrutiny on Wednesday following reports workers would need to lay about 260 metres of track each day, about 10 times the current average, to meet its original April 2018 finish date.
Mr Foley conceded Labor would have to deal with inheriting the light rail if it wins the election.
"We'll look at what options there are, but I can't hide from the fact that this light rail track will run down George Street and every future government will struggle with that reality."
Transport Minister Andrew Constance has been contacted for comment.