Plans to open England's longest subterranean cycle route under a Yorkshire hillside could be finalised later this year.
Campaigners believe they are close to a deal to reopen the 1.5 mile-long Queensbury railway tunnel between Halifax and Keithley more than half a century after the last train passed through it.
The Historical Railways Estate which manages the tunnel on behalf of the Department for Transport (DfT) has planned to block up the tunnel for good this summer because of its dangerous state.
But local cycling enthusiasts have persuaded the DfT to hand over the £3m cost of concreting the tunnel shut if Bradford City Council can be persuaded to take it off their hands.
Graeme Bickerdike from the Queensbury Tunnel Society believes the deal can be done.
"Is it sensible to take £3m of taxpayers money, covert it into concrete, and pour it into a black hole?" he asked. "Or do you use that money and invest it into transforming this structure into an asset that can be used to generate money?"
The group claims that the DfT cash will cover almost all of the cost of re-opening the tunnel, while the walking and cycling charity Sustrans has calculated that using it for recreation would boost the local economy by almost £40m over the next three decades.
Norah McWilliam, the campaign leader and a keen cyclist, said linking the tunnel to a longer cycle network in the area would reduce car traffic and air pollution.
"And on top of that it's going to be exciting and somewhere where families want to visit," she added.
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A spokesman for Bradford Council said it is working out exactly what it will cost to reopen the tunnel.
"We appreciate the passion and commitment of the groups who want to see the tunnel re-opened as a cycleway and we hope to be in a better position to understand what would be involved financially in re-opening the tunnel later this year," he said.