Twin tunnels from Arncliffe to Kogarah that will make up the first stage of the F6 extension are expected to cost between $2.2 and $2.6 billion.
The toll for a one-way trip on the four-kilometre section will be $1.77 in today’s dollars, but, because travelling on it will also involve using the WestConnex motorway, motorists will pay a minimum of $4.53.
Premier Gladys Berejiklian revealed the new figures on Tuesday when announcing the F6 first stage was fully funded.
Ms Berejiklian said the state budget on June 19 would show how much had been allocated for 2018-19.
Further sections of the motorway were “at an early planning stage”, she said.
Ms Berejiklian said funding for the F6 was part of a “public transport and roads package” in the budget for southern Sydney, with a signalling upgrade on the T4 Illawarra and T8 Airport lines to provide extra train services.
Ms Berejiklian said an environmental impact assessment for stage one of the F6 would be released later this year and tenders called next year.
Read more: Could the F6 extension be finished by 2025?
Roads Minister Melinda Pavey said it was expected the project would be completed in 2024 and the government would look at ways of alleviating traffic congestion around the southern end, President Avenue, Kogarah.
Mr Berejiklian said, “For too long the people in southern Sydney have put up with traffic congestion”.
“They have heard governments talk about the F6 and not done anything about it. We are committed to this project, and it’s full steam ahead.”
Ms Berejiklian said it was estimated the twin tunnels would take more than 10,000 vehicles a day off General Holmes Drive and 2000 trucks off streets in the area.
“It will allow drivers to bypass 23 sets of traffic lights and save up to 15 minutes on each journey,” she said.
Ms Berejiklian said the design included connection tunnels to facilitate future components of the F6 between Kogarah and Loftus, which were “in development”.
Transport Minister Andrew Constance said road and rail investment made an “incredible state budget for the people of Sutherland Shire, the Illawarra and South Coast”.
“We are we going to overhaul completely the way people move around southern Sydney from unclogging the trains and improving the T4 to building the first stage of the F6,” he said.
“It’s an incredible investment in billions of dollars for those who have endured for too long,” he said.
“This is completely a congestion busting budget from a roads and transport perspective, and its proof we can do both projects at the same time, so everyone benefits.”