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79 > 85 when 84 > 82

You are here: Home > Forum > Simulations > Released > London Bridge > 79 > 85 when 84 > 82

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79 > 85 when 84 > 82 13/06/2018 at 15:14 #109628
DaveBarraza
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Borough Market Junction:

With a route in from 84>82 and the track in advance of 84 vacant, the crossing points are available to move from normal to reverse if 79>85 is requested.
Under the same conditions but with a train in advance of 84 the crossing points become locked normal and 79>85 is no longer available.

Since 84>82 prevents any move over the crossing points normal, they should probably get thrown reverse when 84>82 is lined up so a potential move 79>85 is available. I'm used to a route lock on the crossing points after forcing them reverse by 84>82, but that might be a NYCT thing.

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79 > 85 when 84 > 82 13/06/2018 at 16:42 #109630
MarkC
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In the attached picture I have set the route from 84 to 82 and have set arrows at 2 sets of points both in the normal position and it is possible to set the route from 79 to 85.

Before setting the route 84 to 82 did you have a train routed from 81 to 85 and once you were able to did you then set the route from 84 to 82?


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Last edited: 13/06/2018 at 16:52 by MarkC
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79 > 85 when 84 > 82 13/06/2018 at 16:52 #109632
Steamer
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The reason is that a lot of the pointwork at Borough Market is covered by one track circuit- see image below showing the extent of it.

Setting a route from 84-> 82 doesn't require the diamond in any particular position, and doesn't lock it. However, once the train passes signal 82, it occupies the track circuit that also covers the diamond, which locks the diamond in position. The route 79->85 requires the diamond crossing normal. If the crossing was reverse when the train passed 82, the diamond can't move normal and the route won't set. If, however, the crossover was normal when the train passed 82, there's no problem and the route can be set.

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Last edited: 13/06/2018 at 16:53 by Steamer
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79 > 85 when 84 > 82 13/06/2018 at 22:36 #109646
GeoffM
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Dave is right - the diamond should be normal (diagonal in the sim) if 84->82 is set. The diamond is correctly deadlocked once a train occupies the track highlighted by Steamer, albeit not necessarily in the correct position.

Mantis 20803 applies.

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79 > 85 when 84 > 82 15/06/2018 at 04:16 #109675
DaveBarraza
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That makes sense, there's only one valid path, so no second track circuit would be required.

It seems like this reduces flexibility - It's a scenario when a route is unavailable due to sequencing, not safety, which I find (IMHO) unusual.

I was taught: "If points not located within the actual route will become locked, and one of their two positions could be used in a different route, then force the points into the 'useful' position when calling the first route."

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79 > 85 when 84 > 82 15/06/2018 at 16:21 #109688
Steamer
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DaveBarraza in post 109675 said:
It seems like this reduces flexibility - It's a scenario when a route is unavailable due to sequencing, not safety, which I find (IMHO) unusual.

I was taught: "If points not located within the actual route will become locked, and one of their two positions could be used in a different route, then force the points into the 'useful' position when calling the first route."
The bug Geoff raised above is to implement the control you describe- it was omitted accidentally.

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79 > 85 when 84 > 82 15/06/2018 at 21:50 #109695
DaveBarraza
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Did not know that Mantis was bug tracking system. Gah!!

Thanks.

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