Motorists who now drive for free along the M4 will face tolls of more than $4 each way in four years, but the government cannot say how much time they will save when the road is widened.
Roads Minister Duncan Gay was incapable of providing the estimate on Thursday, as he defended the government's refusal to release estimates of how many people will use the $11.5 billion WestConnex motorway.
Internal workings had never been made public for road construction and "nor are we going to do it in this case to make certain sections of the media happy", Mr Gay said.
He was speaking after an industry briefing on Thursday, where he announced that Business Council of Australia president Tony Shepherd would chair a new government authority to deliver the WestConnex project.
The first stage opened to the public will be the existing M4 motorway widened to four lanes in each direction between Church Street, Parramatta, and Homebush Bay Drive, Concord. This motorway is at present free, but it will have a maximum toll of $3.90 when it is widened by 2017, expressed in 2013 currency rates. With inflation, that will rise above $4.
Asked how much time motorists would save in return for the toll, Mr Gay initially said "the first stage will not have a $3.90 toll on it", even though the figure was included in his press release. He then said motorists would enjoy a time saving, but could not quantify it.
"There will be a time saving because one of the biggest pinch points at the moment is that section around about James Ruse Drive. Putting the extra two lanes through there will remove that key pinch point and it will be a faster trip," he said.
A spokesman for the Sydney Motorways Project Office later said estimated time savings would be in an environmental assessment, to be exhibited next year.
The government has still not finalised its plans and was keen to tell the finance and construction industry it was open to changing its mind on some aspects.