Converting the disused railway between Armidale and Glen Innes would be worth millions of dollars to the New England economy in tourism.
That's according to a business case which recommends converting the rail line into the New England Rail Trail. The document was made public for the first time on Friday.
The business case shows the $20 million project makes financial sense.
If completed the scheme would create a benefit nearly five-and-a-half times greater than its cost, the document says.
"At present the rail corridor between Armidale and Glen Innes represents a wasted asset, which is costing the NSW Government about $54,140 per year," it says.
"It has been calculated that the New England Rail Trail will attracted 15,000 new day visits and 14,000 new overnight stays to the region annually as well as being used around 37,000 local residents."
The project would be worth $5.8 million to local business and would create 26 full time jobs.
It would rejuvenate small villages like Ben Lomond and Llangothlin, which no longer have any viable retail businesses, the report says.
And the 103-kilometre rail trail would cost just $1,502 per kilometer to maintain, the report says. It should be a relatively-wide 2.5 metres, suitable for both cyclists and walkers.
Chair of New England Rail Trail Incorporated David Mills said they had been waiting for this moment for seven years.
"The numbers are very robust [in the report]. They've been done by the pre-eminent trail designers, with costings that are relevant to our local community," he said.
"Fencing contractors have provided details on fencing costs.
"Bridge engineers have looked at the bridges to assess the stability of them.
"We've looked at continuing stock movements by gate and bridge systems on the corridors.
"We've looked at trail heads at strategic locations, amenity facilities..."
Mr Mills was "certainly pleased - very pleased that it was a very positive report [an] affordable project with lots of outcomes that will beneficial for the community, small business and the region."
Built in the late 19th century, the Great Northern Line has been closed to revenue service for 31 years.
But it remains a legally gazetted railway line which cannot be used for any other purpose. Change requires an act of parliament to convert it into Crown Land.
The rail trail business case anticipates extensive public consultation through 2021 while winning approval to legally close the railway, before start of construction in 2022. The new rail trail would be commissioned by October 2024.
The business case was funded through public donations plus a donation from both Glen Innes Severn and Armidale Regional Councils. Glen Innes councillors will this week decide whether or not to apply for grant funding and commit to back the project.
The document, completed by a consultant from Haliburton, says the calculations in the business case are based on conservative estimates.
Mr Mills said the the project was committed to using local contractors.