WATER lying under Glasgow's roads could be causing sinkholes to appear across the city, it was claimed today.
As motorists and pedestrians continue to complain about the dips appearing in city streets, which have been highlighted in the Evening Times, a leading civil engineer said he believes subterranean water may be to blame for the problems.
Ronnie Hunter, vice-chairman of the Institution of Civil Engineers in Scotland, said: "The most likely cause of the holes appearing in Glasgow is water lying underneath the roads."
"Water flow can be caused by numerous things.
"It may be caused by basement leakages, burst water mains and in some instances leaking sewers.
"In extreme cases it may be to do with underlying mine shafts."
His comments come as Scottish Water is currently investing millions of pounds in upgrading miles of water mains in the city to reduce the risks of bursts and leakage.
Other possible explanations include; old waterways underneath the city could be causing the subsidence; or earth movements, including small earthquakes, could create weaknesses in the subsoil that water can then work through; or the continual digging up of roads by utility companies.
Just last week the Evening Times highlighted the latest sink holes to appear in the city centre.
Three separate instances of subsidence in Waterloo Street, Renfrew Street and Renfield Street appeared in a matter of days, causing misery for drivers and pedestrians.
It followed other stories of sink holes reappearing after repairs being carried out.
In Renfrew Street, at the junction with West Nile Street, a sinkhole has been cordoned off for more than two months.
At the start of the year, work was carried out on the street in a six-month, £400,000 gas mains replacement programme.
In June 2010, we reported a deep hole at the same junction, which caused a major road collapse.
Mr Hunter said water would drain into any voids left beneath the re-laid road surface.
He said: "If the water flows continue into the voids, sooner rather than later the road collapses.
"In order to solve the problem and fix the affected area engineers will have to open up the road to find the source of water.
"Once they have discovered the source, then it is a case of rebuilding the whole surface."
Trevor Davies, senior lecturer in Infrastructure at Glasgow University, said there are many reasons that would normally occur that form the appearance of sink holes in Glasgow.
He said: "Usual reasons include the existence of old mines under the road.
"However, the dissolving of carbonate rocks, possibly old water courses or problem waters beneath the surface could be what is causing it here in the city.
"In all honesty it could be any number of things."
Evening Times columnist and historian Geoff Holder said genuine sinkholes tend to be caused by water working through weaknesses in the subsoil.
He said: "These weaknesses could be the result of pre-existing geological faults, man-made structures (such as tunnels, mines or passages), or perhaps recent earth movements.
"As for mines, there was once a coal mine in George Square, and other mines were located on the South Side and in Springburn.
"A medieval coal mine was found at St George's Cross when the underground was being constructed, but I've never heard of any mines elsewhere in the very centre of the city.
"The other usual suspects would be collapsing sewers or old utility tunnels."
A city council spokesman said: "Glasgow's road network has been established over a long period of history and, over time, thousands of miles of pipes and cables have been incorporated into it.
"These are all potential sources of subsidence."
A spokesman from Scottish Water said: "We are investing millions of pounds in upgrading miles of mains in the city centre and other parts of Glasgow.
"We liaise closely with local authorities, other utilities and stakeholders during the planning and implementation of this work.
"This includes investigations to establish ground conditions."