In message
, at
11:49:19 on Fri, 10 Sep 2010, MIG
remarked:
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 question I hinted at way back was whether there would be any
signalling or tripping affecting the wrong-way train.

I assume a train going the wrong way will activate track circuits just
like any other train.

Obviously, being on the wrong track was something that the driver was
likely to notice,

And if not, why all the palaver abut drivers needing route knowledge
(yes, Tom, even in the dark).

but would the right-way train, stopped by a red light and
occupying the track ahead, make any difference?

Not to the train going the wrong way. But hopefully the right-way train
would not get a green signal, leaving the wrong-way train ages to
discover their circumstances (for example, not having passed any signals
that were intended for them, even if they couldn't see from the
surrounding context that they were wrong-way).
--
Roland Perry

In article , (Roland
Perry) wrote:

In message , at 16:06:36 on
Fri, 10 Sep 2010, Richard J. remarked:

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.

But surely that's what the much-vaunted "route knowledge" (of where
the relevant signals should be) is all about - drivers knowing they
are on a bit of track they shouldn't be.

The safety systems are meant not to have to rely on that alone, though.

--
Colin Rosenstiel

If this failure allowed a train to be signalled onto a wrong direction
track with a train some distance away, held at a signal, then it's
reasonable to also ask whether this same failure would also have allowed
the train to be signalled onto the wrong direction track when there was
a traon 10m away and approaching at 40mph?

i.e. was it just luck that there was no oncoming train in the block or
was the nature of the failure such that it couldn't have happened if the
block was occupied?

I think there's not much we can say until we get to read the RAIB report.

-roy

On 10 Sep, 21:39, Roy Badami wrote:
If this failure allowed a train to be signalled onto a wrong direction
track with a train some distance away, held at a signal, then it's
reasonable to also ask whether this same failure would also have allowed
the train to be signalled onto the wrong direction track when there was
a traon 10m away and approaching at 40mph?

i.e. was it just luck that there was no oncoming train in the block or
was the nature of the failure such that it couldn't have happened if the
block was occupied?

I think there's not much we can say until we get to read the RAIB report.

More than just luck in this case, because no train would be allowed
into the block while a train was leaving the bay, but that doesn't
answer the general point about lack of signalling or (possibly) lack
of tripping once a train is heading along the wrong track.

In article
,
(MIG) wrote:

On 10 Sep, 21:39, Roy Badami wrote:
If this failure allowed a train to be signalled onto a wrong direction
track with a train some distance away, held at a signal, then it's
reasonable to also ask whether this same failure would also have
allowed the train to be signalled onto the wrong direction track when
there was a traon 10m away and approaching at 40mph?

i.e. was it just luck that there was no oncoming train in the block or
was the nature of the failure such that it couldn't have happened if
the block was occupied?

I think there's not much we can say until we get to read the RAIB
report.

More than just luck in this case, because no train would be allowed
into the block while a train was leaving the bay, but that doesn't
answer the general point about lack of signalling or (possibly) lack
of tripping once a train is heading along the wrong track.

The question is how close could the trains have got and how much was
avoiding an accident reliant on the driver of an unsignalled train
noticing the situation and stopping promptly?

--
Colin Rosenstiel

On 11/09/10 07:40, MIG wrote:

More than just luck in this case, because no train would be allowed
into the block while a train was leaving the bay, but that doesn't
answer the general point about lack of signalling or (possibly) lack
of tripping once a train is heading along the wrong track.

But what about the other way round? If a train was already in the
block, could a train still have been routed from the bay onto the wrong
track? Clearly it shouldn't be possible, but then this incident
shouldn't have been possible either?

-roy

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

On 11 Sep, 14:20, Roy Badami wrote:
On 11/09/10 07:40, MIG wrote:

More than just luck in this case, because no train would be allowed
into the block while a train was leaving the bay, but that doesn't
answer the general point about lack of signalling or (possibly) lack
of tripping once a train is heading along the wrong track.

But what about the other way round? *If a train was already in the
block, could a train still have been routed from the bay onto the wrong
track? *Clearly it shouldn't be possible, but then this incident
shouldn't have been possible either?

* * *-roy

Well, true, everything could fail to work I suppose. Not sure where
that gets us.

It seems unlikely that the approaching eastbound train could be
allowed into the block no matter what, either because the departing
train was crossing its path or because the points would be set for it
to enter the occupied bay.

The next question is, is there a legitimate reason why a train could
exit the bay on a green light and go down the wrong line? If there
is, then there wouldn't be any interlocking to prevent it.

Eg, do trains ever come out of the bay and then reverse to head for
Barking sidings? I can't see any possible operational reason for
doing that (would just terminate at Barking in the first place), but
is it signallable?

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

In article
,
(MIG) wrote:

The next question is, is there a legitimate reason why a train could
exit the bay on a green light and go down the wrong line? If there
is, then there wouldn't be any interlocking to prevent it.

If there was a legitimate reason why a train could exit the bay there
would be signals to control the moves.

Eg, do trains ever come out of the bay and then reverse to head for
Barking sidings? I can't see any possible operational reason for
doing that (would just terminate at Barking in the first place), but
is it signallable?

--
Colin Rosenstiel