Because of how old they are there is some really interesting long term data as the earth itself around the tunnels reaches a new thermal equilibrium. In looking

Because of how old they are there is some really interesting long term data as the earth itself around the tunnels reaches a new thermal equilibrium. In looking for a source, i found a good wikipedia article on tube temp in general. These comments and the article made me see how much of it is/was due to braking. TIL. https://en.wikipedia.org/wiki/London_Underground_cooling https://en.wikipedia.org/wiki/London_Underground_cooling