The Prime Minister and Premier of New South Wales have signed-off on a $3 billion tunnel project for Sydney commuters.

The NorthConnex project will now go ahead, which will see twin nine-kilometre tunnels built to connect the M1 and M2 motorways, to be completed by 2019.

The link will allow some travellers to avoid twenty-one sets of traffic lights, and divert 5000 heavy vehicles from lower-capacity roads every day.

“A truck... ­leaving the Port of Newcastle [could] go all the way to Melbourne without going through a set of traffic lights," NSW Premier Barry O'Farrell said.

A $6.11 toll for cars and $18.32 for trucks will help pay for the project.

Fines will be levied against truck drivers who do not use the tunnels when they are completed, according to NSW Roads Minister Duncan Gay.

"We're looking at signage and detection equipment to capture those trucks that don't have a genuine destination along Pennant Hills Road or are not approved to travel within tunnels for safety reasons,'' Mr Gay said.

"We are looking at a fine to ensure heavy vehicles use NorthConnex once it's open to traffic in 2019."

The tunnels have been claimed by both sides of the political spectrum, with the Labor party saying it is a re-hash of a project they had underway last year.

Prime Minister Tony Abbott says Labor had done nothing, and it was up to him to make it happen.

NSW Roads minister Duncan Gay admits he was in talks with the previous Federal Government, but claims it took the “grown up” change of government to actually finish negotiations.

“We started just over 12 months ago with an unsolicited bid and we've worked through in what is record time to give one of the best outcomes for motorists in Sydney,” Mr Gay said.

Federal Opposition infrastructure spokesperson Anthony Albanese says there is no new money from the plan he had been negotiating.

“I signed off indeed in the government party room with Duncan Gay on June 21,” he said.

“Duncan knows this and he's trying to create a media event for Tony Abbott because Tony Abbott has done nothing new on infrastructure anywhere in the country since he was elected. He is the great pretender.”

The Prime Minister says major metropolitan tunnels will benefit the country.

“Better infrastructure will be the hallmark of the Coalition Government and projects such as NorthConnex and WestConnex are part of a nationwide major roads blueprint.”