A two-mile Victorian railway line which was shut down 50 years ago under a programme of sweeping closures could reopen as Britain's longest cycle tunnel.

The disused Rhondda Tunnel, which runs 1,000 feet beneath the Welsh hills, was closed as part of the Beeching cutbacks, a project which spelled the end for thousands and stations across the rail network in Britain.

But engineers are due to visit the 3,148m tunnel next week - for the first time since it closed - to see whether it is safe to use as a cycle route.

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A two-mile Victorian railway tunnel which was closed as part of the Beeching cutbacks could reopen as Britain's longest cycle tunnel

The disused Rhondda Tunnel, which runs 1,000 feet beneath the Welsh hills, was closed 50 years ago

It was shut down as part of the sweeping Beeching Report, which spelled the end for thousands and stations across the rail network

Under the proposals, it would be one of the longest cycle tunnels in the world, second only to the 4,000m Snoqualmie Tunnel near Seattle in the U.S.

It would also mean cyclists could retrace the route where steam locomotives carried coal from the Rhondda Valley to the port city of Swansea - something which supporters believe could be a huge boom to the tourist industry.

Leanne Wood, leader of Plaid Cymru, said: 'There is a real buzz about this project which could transform these valleys if the tunnel is opened up.'

The railway tunnel, the seventh biggest in Britain, runs beneath the mountains under the Dunraven Forest in the South Wales Valleys.

But engineers are due to visit the 3,148m tunnel next week - for the first time since it closed - to see whether it is safe to use as a cycle route

The railway tunnel, which runs beneath the mountains under the Dunraven Forest in the South Wales Valleys, was opened in 1890 in the coal boom. It was then closed in 1968

It was opened in 1890 during the coal boom, after a five-year building project, which was overseen by the tunnel's chief engineer Sydney William Yockney, a pupil of Isambard Kingdom Brunel.

But both ends of the tunnel - at Blaencwm in the Rhondda and Blaengwynfi in the Afan Valley - were filled in during the 1970s.

It came following a report by Dr Richard Beeching, a civil servant from the Isle of Sheppy, who wrote a report called Reshaping of British Railways, which led to far-reaching changes in the transport network.

The engineer had been employed to make the entire network more profitable, prompting him to recommend the closure of stations and railway lines which did not make money.

The tunnel runs from Blaencwm in the Rhondda Valley to Blaengwynfi in the Afan Valley (shown in map)

How the tunnel's length will compare to those around the world, according to the Rhonda Tunnel Society

Under the proposals, it would be one of the longest cycle tunnels in the world, second only to the 4,000m Snoqualmie Tunnel near Seattle in the U.S

Although some 3,000 miles of railway lines were closed before the report, he became infamous for causing the closures of several rural stations. The report became commonly known as the Beeching Axe.

After falling victim to the report, the abandoned Rhondda Tunnel lay dormant for nearly 50 years. But the Rhondda Tunnel Society formed a few years ago in a bid to secure funding for the tunnel's excavation.

The Highways Agency Historic Railways Estate has now contracted a construction and engineering company to undertake the three-day inspection of the tunnel, alongside the Mines Rescue Service.

Rhondda Tunnel Society chairman Stephen Mackey said it would be a 'heart-stopping' three days.

The chief engineer of the tunnel (left) was Sydney William Yockney, a pupil of Isambard Kingdom Brunel, who oversaw the five-year building project which it began in 1885. Pictured right: Workers at the Rhonnda Tunnel

The Highways Agency Historic Railways Estate has contracted a construction and engineering company to undertake the three-day inspection of the tunnel, alongside the Mines Rescue Service

The Rhondda Tunnel Society formed with the sole purpose of reopening the Victorian locomotive route

He said: 'The engineers will be walking the length of the tunnel across three days looking at the safety of the structure to see what it's like after 47 years and to see if it is possible to re-open the tunnel.

'As well as the structural integrity they will be checking for such things as sulphuric acid which can occur in stagnant water and to check carbon dioxide levels to make sure it's breathable down there.'

He added: 'With the interest of the world looking in on the project, the inspections next week are going to be crucial with engineers being in the dark depths of the tunnel evaluating its integrity.

'These are exciting times for us but also a heart-stopping three days. Then we will have the wait for the report and the subsequent findings.'

The tunnel was built by the demands of the coal industry to run from pit villages Blaencwm in the Rhondda Valley under the mountains to Blaengwynfi in the Afan Valley

The plaque at the Blaencwm entrance of the tunnel. It is being inspected next week for the first time since it closed