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Interlocking Fault @ Euston

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Interlocking Fault @ Euston 23/01/2024 at 19:52 #155163
ajax103
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I don't know if this has been reported but surely it should not be possible for a conflict of routes to be set at signals 608 towards Euston at the same time that signal 105 has a route set towards Watford Junction on Line E?

Both signals were able to show a single yellow aspect as I hadn't set the route any further than to the next signal in the case of going from London and to the buffers in the case of going to London.


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Interlocking Fault @ Euston 23/01/2024 at 20:27 #155164
i26
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ajax103 in post 155163 said:
I don't know if this has been reported but surely it should not be possible for a conflict of routes to be set at signals 608 towards Euston at the same time that signal 105 has a route set towards Watford Junction on Line E?

Both signals were able to show a single yellow aspect as I hadn't set the route any further than to the next signal in the case of going from London and to the buffers in the case of going to London.

Mantis 40158 for investigation/to ask the question if this is how it should be.


Last edited: 23/01/2024 at 20:35 by i26
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Interlocking Fault @ Euston 24/01/2024 at 00:05 #155165
Tempest Malice
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As in this scenario no train can approach either signal (being prevented by the route away from the opposing one). There is nothing unsafe here, so it's not a surefire case that it shouldn't be possible.

I understand that modern signalling standards would have an interlocking prevent this, mainly to maintain user confidence in the signalling system. But there is no inherent signalling principle requiring it not to happen, so the interlockings at Euston (or the design of their data at least) may well pre-date the avoidance of this.

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Interlocking Fault @ Euston 24/01/2024 at 09:00 #155166
clive
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Royston, which is a 1977 or so interlocking, has opposing signals (981/982 and 983/984) just like this. The control tables are explicit that you can't set routes from both at the same time. So that's probably been a design principle (at least on Eastern Region) for a long time.
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Interlocking Fault @ Euston 24/01/2024 at 10:27 #155167
Stephen Fulcher
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Last edited: 24/01/2024 at 10:28 by Stephen Fulcher
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Interlocking Fault @ Euston 24/01/2024 at 10:27 #155168
Stephen Fulcher
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You generally cannot do that on Western Region E10k or modern interlockings, route from one requires no route set from the other.

Generally added as someone is sure to know of an obscure exception, but I have never seen it be allowed. For starters each signal would be replaced by a train approaching the other.

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Interlocking Fault @ Euston 24/01/2024 at 17:43 #155170
Zecs
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Actually, it can also be set on lines B (473 and 306), C (309 and 284) and D (287 and 102).
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Last edited: 24/01/2024 at 17:45 by Zecs
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Interlocking Fault @ Euston 24/01/2024 at 23:06 #155180
i26
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Zecs in post 155170 said:
Actually, it can also be set on lines B (473 and 306), C (309 and 284) and D (287 and 102).
I checked this after adding the initial report to Mantis and added it to the report.


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Interlocking Fault @ Euston 25/01/2024 at 08:32 #155183
kbarber
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Stephen Fulcher in post 155168 said:
You generally cannot do that on Western Region E10k or modern interlockings, route from one requires no route set from the other.

Generally added as someone is sure to know of an obscure exception, but I have never seen it be allowed. For starters each signal would be replaced by a train approaching the other.
I have an idea it can be specifically authorised as a derogation where there is an operational need for trains to start away in both directions more-or-less simultaneously, for instance at a location where trains divide. I have a vague recollection of a conversation with my father about Eastleigh. Unfortunately I don't recall whether he was saying the locking there allowed both platform starters to be cleared simultaneously; he may have been commenting on the delays (or difficulty writing an enhanced timetable) because they couldn't. But if anyone has access to control tables for Eastleigh, that would be one to check.

Having said which, the situation uncovered by @ajax103 seems quite different, with the signals back-to-back so a train approaching one would be in the section in advance of the other.

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Interlocking Fault @ Euston 26/01/2024 at 23:07 #155188
DaveBarraza
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The signals are "back-to-back", they share an insulated joint, no? (share a block boundary) - they aren't really "opposing" as they are facing away from each other, like two duelists about to begin their ten paces.

This situation is usually prevented in the US at the route *request* level, but since a train cannot be between the two signals, much less see them both at the same time, no unsafe condition exists. Both signals lock out the route that would allow a train to approach their back-to-back partner so displaying an "approach" on both heads is not especially useful...

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Interlocking Fault @ Euston 27/01/2024 at 13:17 #155194
DaveHarries
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ajax103 in post 155163 said:
I don't know if this has been reported but surely it should not be possible for a conflict of routes to be set at signals 608 towards Euston at the same time that signal 105 has a route set towards Watford Junction on Line E?

Both signals were able to show a single yellow aspect as I hadn't set the route any further than to the next signal in the case of going from London and to the buffers in the case of going to London.


I've just had a look at this. The same scenario is possible with lines C and D.

Dave

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Interlocking Fault @ Euston 03/02/2024 at 17:39 #155240
Guts
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i26 in post 155164 said:
ajax103 in post 155163 said:
I don't know if this has been reported but surely it should not be possible for a conflict of routes to be set at signals 608 towards Euston at the same time that signal 105 has a route set towards Watford Junction on Line E?

Both signals were able to show a single yellow aspect as I hadn't set the route any further than to the next signal in the case of going from London and to the buffers in the case of going to London.

Mantis 40158 for investigation/to ask the question if this is how it should be.
Obviously it under investigation but it's not possible in the actual Box

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