Eden-Monaro candidates Jason Potter, from the Federation Party, and Trevor Hicks, from the Nationals, have thrown their support behind the proposal, declaring it would provide a much-needed boost for the far South Coast region economy and maximise use of one of best deep water ports in Australia.

John Holland Rail, which manages the NSW regional rail service, received $1 million in government funding in August 2018 toward a feasibility study for the proposed link.

Completion of the study was promised by June 2019 but now, a year further on, is still not publicly released.

After Prime Minister Scott Morrison announced earlier this month that $72 billion would be ploughed into regional projects, the Eden rail link proposal has gathered fresh impetus.

It would be primarily a freight link, with some passenger trains, and comprise three sections: Canberra to Cooma, Cooma to Bombala and Bombala to Eden.

The construction cost would be around $2.54 billion over five years, but provide a cost-benefit two-and-a-half times that, according to the study's estimates.

"We've done our own investigations and believe it would be tremendously beneficial for the state, engineeringly feasible and economically viable," engineer Edwin Michell said.

"It would be very informative to have the full study released after the people of NSW have paid for it."

The proposed Eden link would also aim to knit near Cootamundra to the approved Brisbane to Melbourne inland rail project, which received funding from the Federal government in the latest infrastructure stimulus package and will comprise 40 per cent new rail.

The former Canberra to Cooma 114km rail link, disused for more than 30 years, would need a complete overhaul with the bridges, ballast, sleepers and tracks replaced.

The benefit is that the existing route, with its cuttings and earthworks, is almost suited to modern rail rolling stock.

The old 93km section from Cooma to Bombala "was not built to as high a standard" as the previous section, Mr MIchell's report says, and needs upgrading to modern standards with deviations to open the curves. Most of the new cuttings needed are less than five metres in height.

However, the most significant cost is establishing an entirely new route from Bombala to Eden, a track length of 106km via Towamba, which would be about three times as expensive as the two other sections at $1.06 billion.

This spectacular section would have double reverse curves, cross the Towamba River, and have a 950-metre tunnel.

A key benefit, of which which both candidates are fiercely supportive, is putting Eden's existing deep water port to more use at a time when other NSW ports are under pressure.