Flexible hose

Always noticed the grey pipe (roughly around 35-40mm in diametre) which runs alongside all the tracks along with other wires etc. Tho I noticed it never really thought too much of it untill today. As I was on the train leaving westbourne park station on the hammersmith and city line this mornig going eastbound I was standing up looking out of the window when I noticed this same pipe. But what caught my mind was that instead of a continuous run it stopped and was connected by a flexible hose which was around 2-3 meters in length. The hose was not in a straight tight length but floppy (didnt look as if there as any support for it). What is this grey pipe that runs alongside the tracks and why was this section different (flexible) to the rest of the line? im assuming it carries water as the flexible part looks like a flexible hose which connects a sink tap to the copper pipe in a bathroom. And if it is water then what use would there be for water to run alongside all the subsurface tracks. They even have leavers/isolation taps every now and then. Also is this flexible hose strong enough to hold the water (or whatever there is inside) as surely rigid pipework is always much more stronger than flexible hose. (trying to compare it with a domestic heating system). Excuse me for my ignorance

If it is water then they should have it run alongside the station edges with sprinklers on them and turn them on in this heat so we can all cool down in this hot weather ;D

That bit was just a silly joke.

sorry