EMERGENCY measures will be put in place at Queensbury Tunnel to make sure urgent safety work can go ahead.

The Department for Transport , which owns the controversial site, has taken the unusual step over fears one of the air shafts may collapse because of its "increasingly deteriorating condition" caused by the amount of water flowing into a shaft.

The work has thrown the re-opening of the tunnel into doubt, with Highways England admitting the safety procedures will make it "more challenging" to bring it back into use.

Campaigners for the tunnel's re-opening say the measures go too far and do not need to be implemented.

Richard Marshall, Yorkshire and North East regional director for Highways England, said: "Today’s emergency measures to stabilise one of the air shafts in the tunnel follows an influx of water over the last weekend of September.

"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.

“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 re-opening 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 who need 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 at the end of 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 the affected area, which is close to an access road used by people accessing nearby properties, needed immediate attention.

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

Queensbury Tunnel Society said they want to see proof an urgent procedure is needed.

Graeme Bickerdike, engineering co-ordinator for the Queensbury Tunnel Society, said the emergency measure is 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 No.2 shaft for many decades, as evidenced by the longstanding brickwork repair within a sidewall that’s otherwise stone-built.

"A trackworker 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."