Roland Perry wrote:
In message

, at 09:07:00 on Tue, 26 Mar 2019, Jeremy Double
remarked:

There's probably around a thousand trains without toilets in and around
London.

I know but it's becoming obvious that this is unsatisfactory.

I’m not sure where you’d put toilets on tube stock without
obstructing the
emergency exit to the next carriage; as you can’t walk through the train,
would you want a toilet in each carriage?

The point is made in the RAIB report that in the event of a train being
unable to move, underground trains behind it are held at stations, so the
problem that arose at Lewisham wouldn’t arise. This seems a very
reasonable approach on a metro-style railway where the trains are not
provided with toilets.

That still leaves the train which is 'broken down' in the tunnel, and I
don't believe the minimum block length on the Underground is fully from
one station to the next, so there could be a train in the tunnel behind
a broken down one.

Actually it's worse than that, because if a train manages to limp to a
station, or breaks down at a station, there's almost inevitably a least
one train at a stand in the tunnel behind it.

Yes, that's probably true on the busier lines with trains every two
minutes.

I think the train behind is then instructed to proceed slowly and couple to
the stalled train ahead.

Alternatively, it can be instructed to reverse to the previous station. If
the platform is already occupied, the reversing train will either couple up
to it, or the other train will also reverse a short distance, so that one
passenger door of the first train can get to the platform.

Obviously, this only happens once they have given up on moving the stalled
train any time soon.