Urban explorers and railway staff are the only people to have seen the decaying remains of the Wortley Curve since it was decommissioned over 30 years ago.
The alternative route between Leeds and Huddersfield that closed in the 1980s hit the headlines this week when it was revealed that it could be re-opened to act as a bypass for HS2 services not calling at Leeds Station.
Plans revealed for alternative rail routes around Leeds to accommodate HS2
It would allow trains to travel between Bradford and Wakefield while avoiding Leeds.
The half-mile stretch of track's connections to Wakefield Westgate and Bradford at Wortley Junction have now been severed. It closed to traffic in 1985 - by this time, very few trains were using it and it was no longer considered economically viable.
Bradford residents were opposed to its closure because it removed the city's direct link with London. Bradford Council were so incensed by the decision that they even threatened British Rail with legal action.
Urban explorers and rail enthusiasts have visited the site, which is now considerably overgrown with trees in the trackbed. Some signal infrastructure, old rails and a bridge over Oldfield Lane remain. Metal thieves have plundered the site, but it's thought that the track could be reinstated relatively easily.
However, rail experts have pointed out that one of the pitfalls of the Curve is that it linked the main line to Wakefield Westgate, which is electrified, with the Calder Valley Line to Bradford, which is not. This would pose a dilemma when it came to allocating rolling stock that could use it.
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What are the HS2 plans involving the Wortley Curve?
It's recognised that HS2 services approaching from the south would need the option of looping around Leeds rather than entering Leeds Station on their way north.
One solution to this issue has been opening a new junction at Stourton.
However, Transport for the North are against this idea, claim it would cause disruption to the large business park in the area and that it could cost up to £800million.
Reports have considered alternative approaches that could boost connectivity between Yorkshire's main cities instead.
One is to extend a proposed junction at Clayton, between Huddersfield and Sheffield, so that faster services could access the East Coast Main Line through Wakefield Westgate.
Another is reinstating the Wortley Curve to enable direct trains to Bradford and Halifax to avoid Leeds.
A government's Oakervee review into HS2 will be published in a few weeks and funding for the Northern Powerhouse Rail project could be announced in March.