Author Topic: permissive signals - cab signalling  (Read 842 times)

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Offline Vladki

permissive signals - cab signalling
« on: April 30, 2017, 06:34:45 PM »
See this save http://server.exp.simutrans.com/debug-saves/permissive.sve (pak128.CS-Ex)
There is an unintentional blockage at nemcanka, but it shows a few bugs with 3/4-aspect cab-signals:
1. even though there are permissive signals (with the white pole), trains are waiting for clearance.
2. some of the signals are at caution when they should be at danger (101,63) - 4 aspect non-permissive, (128,64) - 4 aspect permissive, (106,64) - 3 aspect non-permissive

3. To resolve the blockage disable reverse route on train (7) and send it to (4) selpice, then disable reverse route on train (11) and send it to (15) trnava predmestie.
Watch the cargo train (6) - it will get clearance for one block, but the signall wil show advanced caution, as if two blocks are clear. I have seen similar bug with 3-aspect signal showing clear when the next signal (which also happened to be choose signal as here) was at danger. This will repeat with all the trains following in the sequence. It seems to be limited to the last signal before a choose signal. (116, 63).

The issue 3 happens also if the signals are track-circuit block.

Just an important note - czech 4-aspect signals have one yellow as preliminary caution a yellow+white as caution. So it may look weird if you are used to UK signalling.

Offline jamespetts

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Re: permissive signals - cab signalling
« Reply #1 on: May 07, 2017, 04:28:34 PM »
Thank you for reporting this. Firstly, no. 1 is working as designed, as permissive signals should only work as such when they are not protecting a junction (as there might be a collision with a train travelling full speed in another direction if there is a junction).

As to no. 2, this is difficult for me to track down, as the signals appear to have acquired their incorrect state before the game was saved, so I cannot reproduce the circumstances in which this incorrect state came into existence.

As to no. 3, this is especially tricky to reproduce properly, as setting breakpoints in the debugger seems to result in the next train clearing the section entirely before the signal is checked again, making it very hard to replicate the conditions in which this occurs.

Edit: I think that I have managed to fix no. 3 - would you be able to re-test?
« Last Edit: May 07, 2017, 04:50:13 PM by jamespetts »
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Offline Vladki

Re: permissive signals - cab signalling
« Reply #2 on: May 09, 2017, 10:21:15 PM »
Thank you for reporting this. Firstly, no. 1 is working as designed, as permissive signals should only work as such when they are not protecting a junction (as there might be a collision with a train travelling full speed in another direction if there is a junction).
But look on the line from selpice to nemcanka - it is split in 4 blocks and there are 3 signals that do NOT protect a junction. Yet still they do not act permissively. (116,63), (122, 63), (128, 63)

Quote

Edit: I think that I have managed to fix no. 3 - would you be able to re-test?
Seems to be fixed

Offline jamespetts

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Re: permissive signals - cab signalling
« Reply #3 on: June 04, 2017, 05:27:53 PM »
I have pushed what I think is a fix for the permissive signal problem; would you be able to re-test? I should be most grateful.
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Offline Vladki

Re: permissive signals - cab signalling
« Reply #4 on: June 11, 2017, 01:33:02 PM »
Hello, the fix introduced more weirdness. Signals are permissive, but trains stay in cab-signalling method. For a few tiles they run at drive-by-sight speed (30 km/h) but 2-3 tiles (maybe sighting distance) before reaching the next signal they slow down to 1 km/h and crawl until the come to the signal tile, when they finally accelerate again. I think they should turn to drive by sight, until they come within sighting distance of the next signal. (Just as with track circuit block.)

Offline jamespetts

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Re: permissive signals - cab signalling
« Reply #5 on: June 11, 2017, 02:50:06 PM »
Thank you for the report: I think that I have managed to fix this - would you be able to re-test?
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Offline Vladki

Re: permissive signals - cab signalling
« Reply #6 on: June 11, 2017, 06:40:03 PM »
Thank you for the fix. It is much better now. No vehicles are crawling at 1 km/h. Although sometimes, as in the blockage from the first post, when multiple convoys line up and come in drive by sight mode to a signal at danger, they won't pass it using call-on, but wait for full block clearance. But this happens only if the track gets really blocked, not in normal traffic. So it is not a big problem if not fixed.

Offline jamespetts

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Re: permissive signals - cab signalling
« Reply #7 on: June 11, 2017, 07:03:02 PM »
Thank you - are you able to reproduce a situation where this error occurs reliably?
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