The Angel station
is on the Northern Line
of the London Underground
In the late 1990s they spent a long time rebuilding the station. Whilst doing this they put in escalators
with what was I believe the single longest vertical
rise in at least Europe
. There was great talk about this and how it would make it a much better station.
Everything was working fine, they had checked everything, so they reopened the station. They then immediatly closed it again when they discovered that as soon as a reasonable number of people got on the escalators they ground to a very convincing halt.
When they had specified the motors for the escalators they did not actually take into account that the escalator would be carrying passengers and not just moving the steps. They have since installed more or stronger motors (I don't know which) but let this be a lesson to us all.