On Sat, 08 Jul 2006 09:42:34 +1000 someone who may be Matthew Geier
wrote this:-

It's probably no so much an issue with the Sub-Surface lines with their
larger tunnels and frequent 'smoke vents', but I could see this being a
serious issue with the deep tube trains - if you fit air conditioning to
any new build rolling stock, just where is the AC system going to dump
it's waste heat ?. The tubes are already too hot. A serious amount of
civil engineering would be needed to improve air-flows through the tubes
to carry the waste heat off. (And probably electrical works to increase
the capacity of the traction power network to take the extra electrical
load of the air conditioning plant on each train).

One of the reasons that rubber tyres have not replaced steel ones,
as the proponents of the Paris Metro confidently predicted, is that
the rubber wheels give off a lot of heat, which has to be dealt with
in some way including beefing up ventilation and air-conditioning.


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54