EMERGENCY measures have been introduced to stabilise an air shaft at a historic tunnel.

The Department for Transport, which owns the Queensbury Tunnel site, has taken the unusual step over fears one of the air shafts may collapse because of its “increasingly deteriorating condition” caused by an influx of water.

The work has thrown into doubt the reopening of the structure, with Highways England – which is responsible for managing the tunnel – admitting the safety procedures will make it “more challenging” to bring it back into use.

Campaigners are pressing for the 1.4-mile-long tunnel to be reopened to form the centrepiece of a cycle path network connecting Halifax to Bradford and Keighley and have been fighting moves by Highways England to fill in the Victorian structure.

They claim the emergency measures go too far and do not need to be implemented.

But Richard Marshall, Yorkshire and North East regional director for Highways England, says the move is essential after water flowed into the tunnel at the end of last month.

“The volume of water entering the tunnel from the southern opening not only endangered the safety of our workforce but also caused the first phase of our safety work to be halted,” he said.

“We had been clear that the first phase of the safety work wouldn’t prevent the tunnel’s future reopening.

“However, the infilling of the shaft in this manner means that any reopening is now going to be more challenging.

“We are aware that this news will be a disappointment to those seeking the reopening of the tunnel, however we have no option other than to complete this work immediately to ensure both the safety of those communities living close by and the workforce which needs to maintain it.”

For the first time in more than two years, contractors took the opportunity to carry out a close inspection of the base of shaft two last month, at which point water began to enter the tunnel at what the Highways Agency said was “an unprecedented volume and speed”.

Workers had to abandon equipment and move to a safe area and, within 48 hours, water levels were close to the highest recorded.

Engineers determined that the affected area, which is close to a road used by people accessing nearby properties, needed immediate attention.

Water levels in the southern section of the tunnel mean further inspections of the base and planned strengthening work cannot be carried out.

However, the Queensbury Tunnel Society said it wanted to see proof an urgent procedure was needed.

Graeme Bickerdike, engineering co-ordinator for the society, said the emergency measure was radical and “the engineering equivalent of knocking your house down because a hole has formed in the guttering”.

He added: “There’s been an issue close to number two shaft for many decades, as evidenced by the longstanding brickwork repair within a side wall that’s otherwise stone-built.

“A track-worker refuge five metres from the shaft started to fail about ten years ago.

“Some of the masonry has since collapsed and a bulge has formed, but there’s currently nothing to suggest that this is affecting the ability of the tunnel lining to transfer load from the shaft into the ground.

“Immediately below the shaft, there are no signs of distress and the tunnel’s profile has changed little since construction.”

Campaigners have the support of Bradford South MP Judith Cummins.

She has written to Baroness Vere, minister in the Department for Transport, calling for more information “regarding the necessity of the works and the timeframe involved”.

She is also seeking details of which powers are being exercised to carry out the work.

Mrs Cummins added: “I am concerned that these emergency works would effectively end any chance of Queensbury Tunnel being used for the benefit of the community.”