A push to reopen a rail line in New South Wales, considered the "missing link" between the state's south and west, is gaining momentum, with inspections beginning into the condition of the track.

The Blayney to Demondrille line, which runs through prime farming country in the state's central west, has been lying dormant for about a decade.

Much of the 180-kilometre corridor is now grassed over and washed away, but it has failed to dampen the enthusiasm among the region's leaders for bringing it back online.

A group of councils have been building a business case for reviving the route, which recently received a boost after the NSW Government committed $5 million dollars to help reopen a section of it.

But Blayney's mayor Scott Ferguson said the business case was strong for the whole route to be revived.

"We believe it is the missing link and certainly, we believe there is a business case to make, not only along the rail line that would use it, but certainly we believe it's an important link for the greater western area," Cr Ferguson said.

He said bypassing Sydney and developing a freight route south into Port Kembla would help grow the inland New South Wales economy.

Condition of rail corridor under spotlight

Early estimates have put the cost of the project at up to $40 million.

A study is now underway to get a clearer picture of the costs, led by the company Lycopodium Infrastructure.

Its managing director, Stuart Sutherland, has been walking along parts of the corridor this week to find out what shape it is in.

He said it was overall in pretty good condition.

"As we've gone, we've observed that the majority of the corridor is still there, and rail is a long life asset so you wouldn't expect major deterioration," Mr Sutherland said.

"We've seen some areas of washaways but in the scheme of things, they're fairly isolated."

While much of the Blayney-Demondrille line is overgrown with grass and parts washed away, consultants say it is still in overall good condition. ( ABC Rural: Gavin Coote )

Mr Sutherland said the priority would be to try and get at least part of the corridor reopened.

"The first prize for this line would be a partial reopening, potentially to Cowra, and I think we could see some commodities start to move back onto the main south," he said.

"But the ultimate game would be to reconnect the strategic blueprint that was really developed with John Whitton, the father of New South Wales, over 100 years ago.

"It's sad to see, in a lot of respects, that some key trunk regional lines like Blayney-Demondrille are non-operational.

"Because if you look at the strategic connectivity you get out of this, you connect the main western line with the main southern line, and from that should bring economic growth for the region."

He said for rail towns such as Carcoar, the economic benefits of having trains roar through the area again would be enormous.

"It's certainly an empty feeling coming out here and feeling the crunch of the ballast and the birds in the background," Mr Sutherland said.

"But what that low groan of steel wheels on steel rails gives you is that prosperity."