Published 06 February 2017
West Dunbartonshire Council has confirmed that extensive works to fill a 62 metre deep hole under Kilbowie Road in Clydebank could take as long as six months to complete.
The collapse in the road was caused by a mineshaft that was not recorded on any historical maps of the area. Experts from the Coal Authority, which manages the effects of past coal mining, have taken responsibility for the site and the repair works to the shaft, which will take between six and eight weeks.
Only a six-metre deep hole is visible from the road surface, but this leads underneath to a shaft stretching down a further 56m to a total depth of 62m – the equivalent of 14 double decker buses.
Work began on site last week, with stone, pressurised grouting and a concrete plug needed to be poured down the hole to stabilise the surface. Once the shaft is filled and capped, work can begin on filling the gap above the shaft and the road reconstruction.
This element of the project could take up to 16 weeks to complete as the repairs are further complicated by the significant infrastructure underneath the road such as pipes, drains and power and utility cables.
The Coal Authority is responsible for the site and reinstatement of the shaft and the Council will take the lead on the reinstatement of the road.
The Council is doing everything it can to support residents and minimise the impact. More than 160 road signs have been placed across the area to inform residents of the works, and a traffic management strategy to divert and manage vehicles has been developed in consultation with Police Scotland. This will be regularly reviewed based on the latest traffic flow information.
Ronnie Dinnie, the Council’s Strategic Lead for Environment and Neighbourhood, said: “This is the biggest collapse ever seen on one of our roads. It is like an iceberg in that what is visible from the surface is only a fraction of the true size of this sink hole. To put this into perspective, the depth is greater than the height of the nearby Titan Crane.
“We are grateful that the Coal Authority, the country’s lead organisation on mine shafts and their remediation, is leading this project and they will move as quickly as possible.
“I know how frustrating this traffic disruption is to our residents but it’s crucial that we get this resolved and the ground is stabilised so that it can be made safe for residents and all members of the public to travel on this stretch in future. “
Tim Marples, Head of Public Safety and Subsidence for the Coal Authority, said that work to restore the collapse in Kilbowie Road has already begun.
He added: “The unrecorded shaft at Kilbowie Road is one of our top operational priorities and our prime concern is the safety of the public.
“Our engineers have designed a solution to safely fill the shaft and repair the road and we are working with West Dunbartonshire Council and the utility companies on our proposals.
“This particular repair is complicated by the exposed utility services within the 62 metre deep void, which we are working to protect.
“From our experience, the work will take between six to eight weeks to complete and cost in the region of £250,000.
“Our aim is get the road re-opened as soon as possible to minimise the impact on local residents and traffic. We apologise for the inconvenience and disruption caused presently and during the forthcoming works.”
Further updates will be provided to the community through the Council’s social media channels and websites once the remediation programme is prepared. The road closures at Kilbowie Road and Milton Douglas Road will remain in place to allow the Coal Authority to progress the works.