02-07-2011, 09:04 PM
I was hoping for a brief sketch, but never a screenshot carefully annotated- wonderfully clear, thanks very much.
Never heard of quite that sort of thing happening, but we do certainly have incidents. Actually I can't readily think of a depot with as much signalling- I expect that the new Eurostar depot might have, but I have never been there.
The lack of anti-preselection should have been found by testing prior to commissioning (but one must admit that occasionally such things slip through).
On the assumption that the 2nd signal would not have cleared (I envisage that whereas the final track might perhaps not be required clear in the aspect all the intermediate ones would be proved), then to NR principles the route shouldn't have been released even with the track sequence. I can see that the passage of the first train would have satisfied the Approach Locking condition, but for TORR to occur not only is another track operation needed in the sequence (actually since this is not a passenger move this isn't mandatory but for your layout they'd be no reason not to implement), but more importantly the "signal stick" has to be proved disengaged, thus proving that the 2nd signal had been off and was replaced by the passage of a train from its berth to the stick track. Hence, to NR eyes, this looks like something else wrong that should have been found in testing.
Definitely agree with you; it doesn't look well designed. I think that I might be letting the contractor know that if he wanted any more business from me that he'd better buck his ideas up and resolve the issue.
Never heard of quite that sort of thing happening, but we do certainly have incidents. Actually I can't readily think of a depot with as much signalling- I expect that the new Eurostar depot might have, but I have never been there.
The lack of anti-preselection should have been found by testing prior to commissioning (but one must admit that occasionally such things slip through).
On the assumption that the 2nd signal would not have cleared (I envisage that whereas the final track might perhaps not be required clear in the aspect all the intermediate ones would be proved), then to NR principles the route shouldn't have been released even with the track sequence. I can see that the passage of the first train would have satisfied the Approach Locking condition, but for TORR to occur not only is another track operation needed in the sequence (actually since this is not a passenger move this isn't mandatory but for your layout they'd be no reason not to implement), but more importantly the "signal stick" has to be proved disengaged, thus proving that the 2nd signal had been off and was replaced by the passage of a train from its berth to the stick track. Hence, to NR eyes, this looks like something else wrong that should have been found in testing.
Definitely agree with you; it doesn't look well designed. I think that I might be letting the contractor know that if he wanted any more business from me that he'd better buck his ideas up and resolve the issue.
(02-07-2011, 10:03 AM)onestrangeday Wrote: Hi PJW:
I have included the track layout for better understanding.
I agree with you, maybe the risk is not high, but it can be improved and be better designed. (has this ever happened in UK)
once again thanks for your explanation
PJW