The 117-year-old Glasgow Underground (opened December, 1896) - the third oldest such system, after London (January 1863, during the American Civil War) and Budapest (May, 1896) - has been blighted by water seeping through the tunnel walls and tracks since it opened - because much of the city is built on a floodplain. Now there are plans to use that water to create what could be a first in subway heating systems.
Scientists at Glasgow Caledonian University are to work with Strathclyde Partnership for Transport (SPT), the regional transport body in charge of running the subway, to change "a negative into a positive" by developing a financially and environmentally effective method of harvesting heat from the ingress water.
The plans involve using heat pumps to suck up the water and the heat which can be used to warm the stations and nearby buildings. If successful, the technique would cut both heating and maintenance costs and reduce disruption for passengers.
The River Clyde cuts diagonally across the subway, between Patrick and Govan stations to the west and St Enoch and Bridge Street to the east, while water also leaks in from the River Kelvin which bisects the subway at Kelvinbridge station.
As the soil surrounding the subway is made up of silt, sand and gravel it is impossible to prevent rain and river water soaking through, forcing the operator to continually pump water back out to prevent the network from flooding and disrupting services.
The project, funded for two years, will be the first to attempt to use the heat-harvesting technique in a subway. It is already a fairly common method for providing ground-source heating for homes. Water in the tunnel has a temperature of around 14ºC, which is sufficient for extracting heat.
A regular complaint about the Glasgow Subway - ironicically nicknamed the Clockwork Orange, deriving from the colour of carriages and Anthony Burgess's 1962 novella - is shorter opening hours compared to other cities due to the amount of maintenance it requires.
It is open from around 6.30am to 11.30pm from Monday to Saturday, but only 10am to 6pm on Sundays. Engineers check the tunnels for leaks and other faults every night, with more extensive repairs carried out at the weekend.
Dr Nicholas Hytiris, a geotechnical specialist in the university's school of engineering and built environment, said: "SPT has expertise in the current methods and systems used to maintain and manage the water in and around its subway tunnels. We will support the company in developing specific knowledge in the analysis of ground conditions within the subway system, how to take a geological surveys and measurements and the interpretation of these results for locating heat pumps."
One of the first tasks for the researchers will be to walk the length of the subway photographing the tunnels and collecting samples to help identify amounts of water seeping in and its quality, which will help determine how easy it can be to convert into heat.
The work will be done as part of a £136,000 Knowledge Transfer Partnership between the university and SPT.
Gordon Maclennan, chief executive of SPT, said: "This is an exciting opportunity for SPT and builds positively on our existing energy-efficiency strategy. We've already installed solar panels and voltage regulation systems at Buchanan Bus Station, a ground-source heat pump at our subway depot in Govan and LED lighting across all of our facilities, but we're always keen to improve our green credentials.
"This innovative approach has potential to produce many more benefits for SPT including reducing our energy usage and costs."
Professor Mike Mannion, GCU Vice-Principal and Pro Vice-Chancellor (Research), said the project was an "excellent example of the way our academics apply their knowledge and understanding to solving practical problems".