On Tue, 7 Jun 2005 17:58:32 +0100, Tom Anderson
wrote:

Why on earth was a train allowed to enter a section of tunnel leading to
points which were known to be broken, with three trains ahead of it? I
appreciate that the station supervisor at Marble Arch thought he'd solved
the problem, but until the points were in a known good state, they should
have been treated as broken. That train could have been emptied much
faster if it had been waiting at the platform, time would have been saved,
and unnecessary suffering prevented.

This is a guess as I've seen no other information on this incident.
Happy to be corrected by any Central Line drivers if I haven't got the
full knowledge of what happens with the Central Line in these
situations.

Policy is to try to get trains berthed in platforms if at all possible.
With the peak service on the Central it is likely you will get trains
between stations in the tunnels.

The points at Marble Arch would have been "scotched and clipped" to fix
them in the appropriate direction (i.e. for the normal line running and
not the siding). Once this was confirmed the trains then receive
instructions to move at normal speed as the line is automatically
operated. Once the first train started to move the system would then
progressively move the following trains and thus it is more than likely
that another train would end up between stations. The presumption would
be that "through running" had been restored. What no one expected was
that the points would be in the wrong position and then be clonked by
the first train through.

Also, i'm not sure what was happening with trains further back than
Lancaster Gate, but it seems to me that it would have made sense to bring
the last train in the queue back to the station as soon as the problem was
detected. If it was resolved, it could have started going forward again,
and since the time to reach Marble Arch would have been dominated by the
time taken for the queue to empty, no time would have been lost. If it had
not, it would have made detraining that little bit quicker, plus it would
have given passengers the opportunity to leave the train instead of
waiting.

The queue in such a situation would be jam all the way back to White
City as that is the next nearest turning point. Reversing trains
(i.e.back up the tunnel as opposed to crossing over to the other line)
is not a normal procedure and where there are computerised systems they
are normally set to detect reversible moves as "illogical" and to take
appropriate action to prevent such moves. As Clive said you need to take
special steps to prevent all other train movements if you decide to
reverse a train against its normal mode of operation.
--
Paul C


Admits to working for London Underground!