On Thu, 3 Apr 2008, Tristan Miller wrote:

What is the purpose of the "open" buttons on the doors of the London
Underground carriages? On every Underground train I've used, the doors
open automatically at every station. Is/was there a time or place where
they don't open automatically and the buttons must be used?

Yes - the past. It used to be the case, AIUI, that the driver didn't open
all the doors when the train stopped at a station on the surface, at least
if it was cold and/or wet and not too busy. Then, you'd have to push the
button to open the door. However, this seems to have been too confusing
for passengers, and now all doors always open all the time (except when
they don't).

tom

--
Through the darkness of Future Past the magician longs to see.