John Rowland wrote:
Brian Watson wrote:

This got me thinking literally, "are there any depots or
strategically-placed triangular junctions at which a train could be
turned right round?"

LU trains are not, as far as I know, biased to be driven from one end
or the other,

But you can't necessarily couple the north end of one train to the south end
of another identical train, unless the original trains were facing the same
way as each other.


I think more of it tends to be able to couple both ways nowadays. The
C stock on Hammersmith, Circle and Edgware Road lines always could, for
obvious reasons. The A stock on the Metropolitan could as well
(although now many units only have the driving equipment at one end),
for less obvious reasons. I suppose because of Watford.

The CO/CP/COP stock could only couple one way, and did sometimes run on
the Circle till C stock took over the Edgware Road branch. They
managed to get it back to the District Line facing the right way.

The Northern Line stock could only couple in one direction but, because
of Kennington, half the units could never couple to the other half.
They seemed to cope somehow. The same on the Picadilly after Terminal
4 was opened.

I remember the 1962 stock on the Central always facing the right way
for years, despite the obvious loop. Maybe anything that went in the
depot from the Grange Hill end always left that way, but then one year
in the 1980s or so they seemed to stop bothering and it ended up fairly
random.

Given that all BR and some Underground stock had universal couplers, I
never understood by the Underground gave itself the problem of
couplings that had to face the right way.



but I could see circumstances such as the Circle Line
where it could be an advantage to turn a train to even out wear on
the wheels.


There's no dedicated stock for the Circle anyway. Also, even on a
non-circular line like the Central, that would mean that the north side
got more worn out, because of the way it bends and so on. I wonder if
it's really a problem?



There are no such facilities in depots. The two obvious triangular junctions
which can turn a train are visible on the tube map near Gloucester Road and
Aldgate. There is a non-obvious one linking Moor Park, Croxley and
Rickmansworth. The two obvious loops for turning trains are shown on the map
at Heathrow and Leytonstone-Hainault-Woodford, and the non-obvious one is at
Kennington, allowing trains from Goodge Street to head back to Goodge Street
without reversing. Trains cannot be turned on the Bakerloo, Victoria,
Jubilee, or East London Line without a significant trip on another line, and
trains cannot be turned on the Waterloo & City without being lifted by
crane.