h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

How is it possible for the Deep-Level tube trains to rock and sway as violently as they do? My girlfriend and I were in London in September of 2005 and quite simply fell in love with the Underground. One thing that puzzles me however, is that as you watch a Deep-Level train enter a platform, there isn't but maybe 2 - 3 inches of clearance between the train and the tunnel walls yet the train sways much more than that as it's hurtling down the line at full speed. How does it not scrape the tunnel walls?

The reason is that the tunnel and the tracks are doing most of the swaying. Despite the fact that the tube map shows a bunch of perfectly straight lines, the tunnels actually change direction all the time, turning sideways and passing up and down inclines. The fact that you can't see anything but the tunnel makes it seem as if the train is swaying, but it actually doesn't sway nearly as much as you'd think - it's just the 'centrifugal' force of the bends the train takes.

Alex

Thank you Alex. I'm well aware that in reality the tube lines in no way resemble the neat layout of the tube map. Part of it's charm for my girlfriend and I is the twisty, curviness of it all. The swaying that I refer to is not only felt but is visible as you look forward or behind into the adjoining cars. There is alot of movement going on there as the cars sway significantly in opposite directions. I suppose it is somewhat of an illusion as the cars swaying in that manner would visibly double the amount of actual movement. Still, I bet if you would attach a chunk of styrofoam, or like material, an inch or two thick, to the outside of a Deep-Level train, it would be shredded from contact with the tunnel walls by the time you reached the next station. Hey, that sounds like a fun experiment to try. Think the LU would go for it?

Yep - it probably would get shredded as well as horrifically dirty, as the sway in the tunnel makes the train sway - but I don't know if the LU would like it...