Cooling down underground

London Underground may finally have found the answer to sweltering conditions on the tube. A trial is planned for next summer of a system that will pipe cold ground water through deep level tunnels to help cool the system.

Air cooled trains have already been ordered for the network’s sub-surface level lines, and the first batch will go on stream on the Metropolitan line in 2009. But a more innovative solution is required for the deep level lines where temperatures last summer became unbearable during Europe’s hottest summer for 500 years.

A spokesman for London Underground said: “With the sub-surface lines, air cooled trains are a viable proposition because the heat can escape from the system much easier. In the deep level tubes, it’s not just a case of getting heat off the trains because then you’d be dumping it into the tunnels and stations and making them even hotter. So, the issue is how to get the heat off the system.

“One method we’ve been looking at is the potential to use cold ground water. It would be piped through the tunnels into heat exchangers to cool the environment, the water then soaks up some of the heat and is flushed out of the system.”

The solution has been researched by London Underground’s engineering department in conjunction with the South Bank University. If successful, it could take the £100 000 prize offered by London Mayor Ken Livingstone in 2003 for anyone who could come up with a viable solution to the problem.

The “Cooling the tube” competition received 3400 entries and has yet to produce a winner. London Underground Electrical and Mechanical Engineer Ernie Boddington said: “We are taking some entries forward for further consideration and will provide another update in due course.”