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Points P1629 Swinging Overlap Timer Expired

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Points P1629 Swinging Overlap Timer Expired 07/02/2021 at 22:00 #137071
Rocangus
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Yesterday I was happily playing SimSig on Three Bridges in my chain when this message appeared:

18:05:04 Points P1629 Swinging overlap timer expired

Relevant saves attached.

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Points P1629 Swinging Overlap Timer Expired 08/02/2021 at 12:13 #137077
Dionysusnu
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I believe this means that the points have been in neither state for too long, after the signal behind cleared when the points were locked. The interlocking assumes something is wrong, so it considers the overlap blocked and reverts the signal behind to red. It can happen in a lot of locations.
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Points P1629 Swinging Overlap Timer Expired 08/02/2021 at 12:35 #137079
jc92
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Dionysusnu in post 137077 said:
I believe this means that the points have been in neither state for too long, after the signal behind cleared when the points were locked. The interlocking assumes something is wrong, so it considers the overlap blocked and reverts the signal behind to red. It can happen in a lot of locations.
From a Simsig point of view, it should only happen if the points in question have lost detection due to a failure. It shouldn't happen on a healthy set of points.

I've run through your 18:00 snapshot and I can't reproduce this, and the 18:10 save doesn't give much of a clue, although the points are shown as having correct detection. as this reproducible with further services or a one off?

As explained previously, where the overlap for a route extends over points, the preceding signal will not clear until the route is locked and detected safely, however the points can be then swung while the signal remains clear. if the points don't detect after X seconds, they will revert to their original position and lock to provide a safe overlap and you'll get the message.

"We don't stop camborne wednesdays"
Last edited: 08/02/2021 at 12:49 by jc92
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Points P1629 Swinging Overlap Timer Expired 08/02/2021 at 12:44 #137080
Dionysusnu
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It also happens if you repeatedly key them in opposite positions, without letting them ever lock into either of the positions.
By can happen, I meant that a lot of points have this timer. I didn't mean it happened often.

Last edited: 08/02/2021 at 12:45 by Dionysusnu
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Points P1629 Swinging Overlap Timer Expired 08/02/2021 at 17:10 #137082
GeoffM
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The swinging overlap timer is 7 seconds (per real life SSI), or double that for sims with sequential locking (Australia and, I believe, a forthcoming UK sim with E10k interlocking). Detritus in the point blades can cause an expiry.

The message is not a bug but informational: if a train was approaching any signals affected then you might expect an ACOA.

SimSig Boss
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Points P1629 Swinging Overlap Timer Expired 10/02/2021 at 10:32 #137097
StepSig
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jc92 in post 137079 said:
Dionysusnu in post 137077 said:
I believe this means that the points have been in neither state for too long, after the signal behind cleared when the points were locked. The interlocking assumes something is wrong, so it considers the overlap blocked and reverts the signal behind to red. It can happen in a lot of locations.
From a Simsig point of view, it should only happen if the points in question have lost detection due to a failure. It shouldn't happen on a healthy set of points.

Are you sure this is the case, as I'm sure I managed to do it (by not waiting to detect before swinging back a set of points that I moved by mistake)?

Edit - I'm pretty certain this was on Saltley, though I'd need to check that and see where the error was if needed

Last edited: 10/02/2021 at 10:38 by StepSig
Reason: Albert's post below

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Points P1629 Swinging Overlap Timer Expired 10/02/2021 at 10:36 #137098
Albert
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I believe I managed to do that as well a few months ago, but I'm unsure what sim that was on.
AJP in games
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Points P1629 Swinging Overlap Timer Expired 10/02/2021 at 10:45 #137099
jc92
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You've answered your own question. If you've reversed then normalised the points without allowing them to detect, that would cause the issue.
"We don't stop camborne wednesdays"
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Points P1629 Swinging Overlap Timer Expired 10/02/2021 at 11:50 #137101
Dionysusnu
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Is this something the timer accounts for in real life, or would it cause the same issue as in SimSig. I would imagine it maybe resets the timer when the "target position" is changed?
Last edited: 10/02/2021 at 11:50 by Dionysusnu
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Points P1629 Swinging Overlap Timer Expired 10/02/2021 at 11:59 #137102
Stephen Fulcher
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Yes.

The real life timer, certainly in relay interlocking areas, (GeoffM will know for SSI) is simply driven off the points being detected neither normal nor reverse.

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Points P1629 Swinging Overlap Timer Expired 10/02/2021 at 12:00 #137103
headshot119
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GeoffM in post 137082 said:
The swinging overlap timer is 7 seconds (per real life SSI), or double that for sims with sequential locking (Australia and, I believe, a forthcoming UK sim with E10k interlocking). Detritus in the point blades can cause an expiry.

The message is not a bug but informational: if a train was approaching any signals affected then you might expect an ACOA.
Per Geoff's post above, the timer is 7 seconds. That's from the moment the loss of detection for the points in the overlap occurs, the only way to reset the timer is to get detection in the points. Changing the requested position of the points will not reset the timer.

"Passengers for New Lane, should be seated in the rear coach of the train " - Opinions are my own and not those of my employer
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Points P1629 Swinging Overlap Timer Expired 10/02/2021 at 16:37 #137108
GeoffM
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Looking at some real life data which should be fairly standard across interlockings, the way it works is that there is a timer object associated with each point set that's involved in a swinging overlap. In this example it's called EP2167 ("E"lapsed timer, for "P"oint 2167).

For the signal that needs the overlap at the following signal proved, the case is:
- all track sections clear
- all points controlled and detected in the correct position, except:
- - points 2167 cdn OR points 2167 cdr OR (EP2167 < 8 AND signal off)
- signal ahead lit, TPWS proved, etc

cdn = controlled and detected normal
cdr = controlled and detected reverse

When a route is called, or the points are manually called, then the timer is only reset to zero if the points were detected normal [dn] (just detection, not control) and they're being called reverse, or if [dr] and being called normal.

So what happens internally is that the timer runs continuously, from zero to 254 (255 is a "stopped" state but is not used in swinging overlap logic as far as I can see) in SSI; higher in Westlock and Smartlock. Changing the point call (eg from normal to reverse while moving to the normal position) does not reset the timer and if an overlap is relying on it to keep a signal showing proceed, then you're going to get an ACOA if the points don't move rapidly.

I believe physically most point machines will complete a movement fully to the opposite position before coming back again, rather than changing direction mid-stroke.

SimSig Boss
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Points P1629 Swinging Overlap Timer Expired 10/02/2021 at 16:43 #137109
GeoffM
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Dionysusnu in post 137101 said:
Is this something the timer accounts for in real life, or would it cause the same issue as in SimSig. I would imagine it maybe resets the timer when the "target position" is changed?
No, because that would be defeating the logic. The timeout is limiting the time that the points can be in a potentially unsafe situation (open blades), like a "hold on sec while I take my safety belt off" followed by "oh no, that didn't work, let's revert to a safe state".

You should be able to re-create the "timer expired" message simply by swinging a point in an overlap repeatedly (ie for 8 seconds, without letting the points fully complete movement) in most sims.

SimSig Boss
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Points P1629 Swinging Overlap Timer Expired 10/02/2021 at 18:16 #137112
Dionysusnu
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GeoffM in post 137108 said:
I believe physically most point machines will complete a movement fully to the opposite position before coming back again, rather than changing direction mid-stroke.
That would be nice if added to the SimSig logic.

Last edited: 10/02/2021 at 18:16 by Dionysusnu
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Points P1629 Swinging Overlap Timer Expired 10/02/2021 at 18:46 #137115
Steamer
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Dionysusnu in post 137112 said:
GeoffM in post 137108 said:
I believe physically most point machines will complete a movement fully to the opposite position before coming back again, rather than changing direction mid-stroke.
That would be nice if added to the SimSig logic.
If I understand rightly, the points are non-detected if the commanded position and the actual position don't match. So even if the points moved correctly to Normal, they still wouldn't be detected if they were last commanded Reverse.

"Don't stress/ relax/ let life roll off your backs./ Except for death and paying taxes/ everything in life.../ is only for now." (Avenue Q)
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Points P1629 Swinging Overlap Timer Expired 10/02/2021 at 19:43 #137118
GeoffM
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Steamer in post 137115 said:
Dionysusnu in post 137112 said:
GeoffM in post 137108 said:
I believe physically most point machines will complete a movement fully to the opposite position before coming back again, rather than changing direction mid-stroke.
That would be nice if added to the SimSig logic.
If I understand rightly, the points are non-detected if the commanded position and the actual position don't match. So even if the points moved correctly to Normal, they still wouldn't be detected if they were last commanded Reverse.
Correct. Though being the railway, I'm sure there are exceptions to the rule.

I've put it into Mantis as an idea, 33014 (ie it's not exactly high priority).

SimSig Boss
Last edited: 10/02/2021 at 19:44 by GeoffM
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