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#31
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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 |
#32
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#33
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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 |
#34
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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. |
#35
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#36
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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 |
#37
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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 |
#38
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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? |
#39
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#40
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