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
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?

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?

tom

--
Re-enacting the future