Bathurst MP Paul Toole will cap a big 10 days on Tuesday when he is officially sworn in to the new portfolio, the first time roads and transport ministries have been split into separate regional and metropolitan portfolios.

It comes after a big win at the state election on March 23 when Mr Toole defied a statewide swing against the Nationals to increase his two-candidate preferred margin and just days after he became deputy leader of the NSW Nationals.

He said splitting the portfolios would bring a greater focus to rural and regional projects.

The Coalition Government has already committed to a $2.5 billion, 31-kilometre duplication of the Great Western Highway between Lithgow and Katoomba, with work to start in the next four years. But Mr Toole said he would also use the next four years to start planning the next stage of upgrades.

"What I want is a safe and fast road from Lithgow to Penrith where you can travel at 100km/h because one of the real frustrations at the moment are all the speed limit changes," Mr Toole said.

"When you get to towns like Blackheath, though, you really can't go around so the only way is to go under so we want to start looking at costings for tunnels in the next four years.

"It's a big job but, who knows, if the feds come on board and give us some real money then maybe we can expedite it even faster than that."

Mr Toole said his new portfolio would also have him overseeing the introduction of a second daily return rail service to Sydney in early 2020 and further Great Western Highway improvements from Kelso to Raglan.

And the state government will take back control of more than 15,000 kilometres of roads across the state from local councils to ease financial pressure on local government.