Why don the trains on London Underground have air conditioning?
A. A number of reasons. First, the climate in the UK is not generally warm enough to warrant the expense of installing air conditioning in houses and it is only put into modern buildings where glass walls increase the ambient temperature. On the Underground, if air conditioning was put onto trains, the waste heat would be dumped into the tunnels. There is nowhere for it to go, so the tunnel temperature would rise even more than it does now. The control of tunnel temperature is a constant battle requiring ventilation plant all over the system and which is combined with draught limitation shafts to keep the wind speeds low enough for comfort and temperatures at a reasonable level. If trains had air conditioning, then it would soon be necessary to air condition the stations and tunnels. This would be excessively expensive. On tube trains, which are smaller than the District, Circle and Metropolitan trains, there is no room to put air conditioning equipment unless you enclose several squar
