[Bug] Trains are squashed together on leaving a depot

[jamespetts]

When a train leaves a depot, very often, a great many of the carriages are squashed together until the train next turns around. The below two screenshots are an example: the first is the train (consisting of a locomotive and four carriages) leaving the depot, and the second is the same train after it has turned around at the end of the track (it was set with a schedule to travel between two waypoints).

The screenshots come from the latest nightly binary, the one with four different version numbers, but the date of the 28th of February 2009.

[prissi]

Usually this happens only when there is a signal or waypoint on a tile directly before the depot.

[jamespetts]

Usually this happens only when there is a signal or waypoint on a tile directly before the depot.

Aha, thank you for the information! There was indeed a waypoint on the adjacent tile...

[Dwachs]

Does this small patch help? I did not test it that much, but afaict trains leaving depot are now rearranged at the waypoints. In fact, they are jumping some space in front. Dont know what happens at signals near depots...

[jamespetts]

Dwachs,

it works, thank you! But, may I ask - why the empty

Code Select Expand


else {
}


statement?

[prissi]

But this solution has the problem, taht a train will jump through a signal and a waiting train and will cause havock. Imho, the only way out would a proper check for too long trains for leaving ...

[jamespetts]

Prissi,

ahh, thank you for spotting that. Pity that it causes further problems...

[Dwachs]

@James: the empty statement was planned to be not empty but never got filled.

@Prissi: The motivation for this patch was that in the code there are several statement (steps_driven>=0 ? LEAVING_DEPOT : DRIVING). However steps_driven is always -1 (?).

[Dwachs]

But this solution has the problem, taht a train will jump through a signal and a waiting train and will cause havock. Imho, the only way out would a proper check for too long trains for leaving ...

This happens also with long trains entering a too short station. If the route on which they leave is different from the route on which they came, the trains are jumping.

Would this help: when the train is reversed in a station move it only to the last common tile of the both routes (new and old) or only to the beginning of the station? Then probably some trailers of the train are off-track, but this happens also if trains have to change their route caused by a change in the track layout, so might be of less harm?

Edit: Another proposal: If a train has to reverse direction in a station but the train is longer than the station then treat the train as it would leave a depot at the end of the station. Patch attached.

[Amelek]

This bug is pretty easy to reproduce, and has huge consequences.

1. Make depot with signal that would block leaving train - for example station choose signal.
2. Make sure that there is enough free space between signal and next blocked title for train to fill.
3. Build the train and send it from depot.
4. Make sure it stops before signal while part of train is still inside depot.
5. Release route.

as you see, now train is as long as part between signal and depot. Not only it looks smaller, but it also acts as if it was smaller: it will release locks after last wagon, rather then after it's real length.

http://www.ii.uj.edu.pl/~szklarze/simscr54.png
http://www.ii.uj.edu.pl/~szklarze/simscr53.png

moderator's note: merged with existing topic --whoami

[Dwachs]

This is a long-known bug.

I once posted a patch for it:
http://forum.simutrans.com/index.php?topic=1609.msg16673#msg16673

The trains get repaired though if they have to turn around.

[prissi]

Needs to be looked at it again to find out, which has less severe consequeces. ut there was also the idea to display a not route in such circumstances.

[prissi]

This is now checked more thouroughly in the recent nightlies. It should not lead to jumping trains on diagonals, please test this.

[prissi]

NObody complains about it => closing