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[email protected] · September 11th 10, 03:52 PM posted to uk.transport.london

In article . li,
(Tom Anderson) wrote:

On Fri, 10 Sep 2010, Richard J. wrote:

Roland Perry wrote on 10 September 2010
15:04:42 ...
In message
, at
04:44:08 on Fri, 10 Sep 2010, Alan Ben It
remarked:
Surely it was still failsafe? No trains were signalled to collide
with each other.

Yes they were. One train was on the line working in the wrong
direction.

And what makes you think the train coming towards it had not been
stopped as a result of the erroneous train occupying a track circuit
(in that sense "ahead of the correctly routed train")?

Just curious; I haven't seen this detail discussed, have you?

The Evening Standard said that there were two signals between the
two trains, both at red, and that a TfL sokesman had said "The
nearest eastbound train was stationary at red signals almost a
kilometre away at West Ham." But of course, as I pointed out in
my post at 13:10 today, those signals only controlled eastbound
trains. There would have been no signals controlling the
westbound train on that track after it left Plaistow. It was
only stopped thanks to the driver's alertness.

There would have been no red signals for the westbound train, true
- but also no green signals. What are the rules about needing a
green signal to proceed? What happens if the power to all signals
somehow fails, or their bulbs all go at once? Presumably, drivers
don't all just merrily put their feet down? Or is there some rule
about needing to see a green light if there's a signal post, in
which case it wouldn't have helped? Or is there a counter-rule that
the driver must see a signal post to proceed?

Huh? Signals can be very widely spaced.

I tentatively think this focus on the lack of signals is a bit
misleading. Ultimately, all safety on non-ATO lines depends on
drivers correctly responding to signals (barring tripcocks - am i
right i thinking these are only present at a fraction of signals?).
If we accept that stopping at a red is an acceptable part of the
safety mechanism, why can't we also accept that stopping at the
absence of a green, or the absence of any signal, is?

Tripcocks are present at all home signals on LUL lines.

--
Colin Rosenstiel