Cooling the tube – Engineering heat out of the Underground
On a hot summers day, a trip on the tube to get home can be a dreaded experience, with already hot trains overflowing with sweaty people. But how did we get to a situation where tube trains are stiflingly hot, and what’s being done about it?
A talk given by London Underground’s Head of Station Systems Engineering, Sharon Duffy, looked into the challenges the tube faces in keeping cool during the summer.
The “tube” can be split into two types of service — the tube proper which runs through tube tunnels, and the older sub-surface lines which are just below street level (pedants get very upset when sub-surface lines are called tube trains).
The older sub-surface tunnels were built for steam trains, so had loads of big holes in the ground included in the design to deal with removing smoke, and they are also much larger than tube tunnels. This has allowed the London Underground to fit air-conditioning units to its new fleet of sub-surface trains (S Stock), and as anyone who uses them appreciates, it’s a boon on hot days to get onto a cool train.
The heat from the air conditioning units is easily vented away when the trains are underground thanks to the pre-existing steam train ventilation.
