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ACOA/unsafe point movement at Northam Jn

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ACOA/unsafe point movement at Northam Jn 18/02/2012 at 12:00 #29656
dmaze
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88 posts
Southampton V3.2.3. I can trigger an ACOA by being wishy-washy around the bidirectional lines east of Southampton Central station, as follows:

  1. Set a route from St. Denys towards Southampton Central through Northam Junction, from the Down Slow line to the Down Main line (707-711-719). Let the Mount Pleasant LC clear, and the points at Northam Junction should swing to accommodate this route.
  2. Set a similar route from the Down Fast line towards the Up Main line (709-713). Again, points swing at the junction for the overlap. This route does not actually need to be on to the Up Main.
  3. Cancel the immediately preceding route.
  4. Now set a route from the Up Main to the Up Fast line.


When this last happens, there is still a route for the train towards Southampton from signal 711 to 719, but signal 711 has gone back to red, and the points have swung back as though the overlap at Northam Junction needed to be set for the DF-DM route.

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Re: ACOA/unsafe point movement at Northam Jn 18/02/2012 at 13:38 #29658
maxand
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1637 posts
Confirmed.













Also happens if setting route along Up Slow.

I initially thought it might have been due to approach release locking of 711 but it's probably a bug.

Note that the Messages window says ACOA at 707, where the train happened to be when I set a route along Up Fast

Last edited: 18/02/2012 at 13:41 by maxand
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Re: ACOA/unsafe point movement at Northam Jn 18/02/2012 at 14:20 #29659
J5flyer
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48 posts
Hello,

I've had this several times in the past, but I never reported it as I didn't know the steps to re-produce it. Well done for figuring it out!

James

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Re: ACOA/unsafe point movement at Northam Jn 18/02/2012 at 14:28 #29661
Stephen Fulcher
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2084 posts
" said:
Confirmed.
I initially thought it might have been due to approach release locking of 711 but it's probably a bug.
It is definitely a bug.

In reality, if a signaller were to attempt to set a conflicting route the interlocking just would not set that route.

However, there is no conflict here so it appears that the bug lies with the route setting for signal 716.

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Re: ACOA/unsafe point movement at Northam Jn 18/02/2012 at 14:58 #29663
andyb0607
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260 posts
Bear in mind that Southampton is one of the oldest released sims. A whole host of new improvements have been made to SimSig in general since then.

If/when this sim is updated I'm sure that it will be put through a thorough testing before it is released.

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Re: ACOA/unsafe point movement at Northam Jn 18/02/2012 at 17:07 #29668
Peter Bennet
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5402 posts
Suspect there is some sort of flank protection coded that causes Point 2 to normalise when Point 1 normalises.






Peter

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Re: ACOA/unsafe point movement at Northam Jn 18/02/2012 at 17:43 #29670
Stephen Fulcher
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2084 posts
That makes sense, however if that is the case the interlocking should not allow the second route to call as the first one is already set, so there is a bug in there somewhere.
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Re: ACOA/unsafe point movement at Northam Jn 19/02/2012 at 09:12 #29679
Firefly
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521 posts
I raised this with Geoff many years back before the forum was born.

He said at the time he'd had a nightmare with the swinging overlaps in that area.

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Re: ACOA/unsafe point movement at Northam Jn 19/02/2012 at 11:18 #29680
GeoffM
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6376 posts
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Clive re-wrote the swinging overlap logic some time ago, but probably after Southampton was last released. Complex overlaps like this area involve recursion before all the routes can agree on which points they want in which position.
SimSig Boss
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