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Author Topic: Potential brive by sight sign bug  (Read 206 times)

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Offline Freahk

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Potential brive by sight sign bug
« on: July 27, 2020, 06:08:37 PM »
When a train approaches a drive by sight sign it slows down until it nearly comes to a standstill and then continues in drive by sight.
This was initially observed when a train was in time interval before, but also happened to a train that already was in drive by sight.

Another rarely arising issue is that some trains will remain at 1 km/h for some time after slowing down.
Both indicate that the target point is not updated properly once the train can see the sign.

I am not sure if that's intended but it seems quite strange to me.

Offline jamespetts

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Re: Potential brive by sight sign bug
« Reply #1 on: July 28, 2020, 11:12:34 PM »
Thank you for the report. It would be helpful to have a reliable reproduction case for this to aid investigations.

Offline Freahk

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Re: Potential brive by sight sign bug
« Reply #2 on: July 28, 2020, 11:20:07 PM »
Now that I know it's not intended, see the attached save for the first behavior.
The latter, I was not able to reproduce yet.
You can observe the train slowing down to roughly 6 km/h at both drive by sight signals. One being aproached in time interval mode, the other one in drive by sight.

Offline jamespetts

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Re: Potential brive by sight sign bug
« Reply #3 on: July 29, 2020, 03:57:07 PM »
Thank you for that - I have now changed the behaviour here so that trains already in the drive by sight working method now ignore end of signalling signs. I should be grateful if you could re-test with the next nightly build. Thank you.

Offline Freahk

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Re: Potential brive by sight sign bug
« Reply #4 on: July 29, 2020, 04:08:40 PM »
I thought the main issue is the slowdown in general.
I would not expect trains in any working method to slow down to less than drive by sights maximum speed. Is that slowdown intended?

Offline jamespetts

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Re: Potential brive by sight sign bug
« Reply #5 on: July 29, 2020, 04:19:09 PM »
I thought the main issue is the slowdown in general.
I would not expect trains in any working method to slow down to less than drive by sights maximum speed. Is that slowdown intended?

The code in question does not directly cause trains to slow down. Rather, it stops the reservation of further tiles beyond the point in question (i.e., the tile with the end of signalling sign on it). This is the thing that gives the end of signalling sign its effect: the signal reservations end at that point.

However, before the change, it would prevent any sort of reservation beyond that tile, including drive by sight reservations. Thus, even when the train had already switched to drive by sight mode because it could see the sign ahead, it would still refuse to reserve beyond this sign, and thus would slow down before the sign. Now, as soon as the train has switched to drive by sight mode, it will no longer cease reservations at the sign, and drive by sight mode reservations can be made beyond the sign.

I hope that this clarifies matters.