Why do you get a lot of wind in underground tunnels in London (or anywhere) sometimes?

Question

That's as in the underground train system or the "Tube" as it's known as well.

I notice it even if outside it's not partcularly a windy day.

Answer 1

In the "olden days" when the "tube" was first developed, ventilation was achieved by lighting a fire at one end of the tunnels, and drawing fresh air through from the other end. - Hot air rises up the flue, but with the advent of large electically operated fans moving vast volumes af air, this practice stopped.  As other posters have said this is assisted by the "close fit" of the trains moving through the tunnels

Answer 2

Trains fitting tightly in small-bore tunnels and moving give the piston effect of pushing air through the tunnels, and if you notice it outside, it's what everybody else calls "It's a bit windy today"......

Answer 3

It's because all of the trains, when they're hurtling down the tubes they're forcing the air down the tunnels... now add the fact that they're hundreds of miles of tunnels and shed-loads of trains... that's a lot of air moving around!

Answer 4

Air exchange system. The Terminals and what not are at a greater air pressure than above ground. Confined subterranean spaces have issues with keeping adequate oxygen levels. The air exchange system pumps air down into the station and the higher pleasure forces it all back up through the entrance to the surface creating a nice dynamic flow.

Ignore the stuff below, I misunderstood the question.

1) there are actually fan systems that recycle the air in tunnels. sucking out the old and replacing it with the new.... this creates a draft.

2) Tunnels (the ones around here) tend to be one way traffic. All the vehicles moving in a single direction creates high volume airflow.

Answer 5

Eating too many baked beans and Brussels sprouts for breakfast!