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Trains randomly ignore switches

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avatar From: OP
Mon, 24 Dec 2018 16:26:01 -0000

Sometimes when a train rides over a rail switch, it goes the wrong way. I

have to ride far back and then try it again. Sometimes even that doesn't

work, I have to switch the track twice and then the train takes the correct


avatar From: Someone else
Wed, 02 Jan 2019 08:29:01 -0000

More specifically: When a train passes the switch in the opposite

direction (from one of the diverging tracks to the common one) and the

switch was set to the other way, the switch will flip to the rail from

which the train went but the graphics does not refer that. When the

train (or another one) then tries to move through the switch, it will

"go the wrong way".

Maybe you shall look at the switch node (and its rotational metadata)

when deciding which way the train shall go instead of using some other

metadata that may become unsynchronized with the switch node.

avatar From: OP
Fri, 04 Jan 2019 16:04:01 -0000

What is strange, this doesn't happen in all cases you described above. Only

something like 30% of switch nodes behave this way. And some of them are

buggy only sometimes.

Also, the graphic should always refer to the current state of switch, so

it's definitely a bug.

avatar From: Someone else
Sat, 05 Jan 2019 12:59:01 -0000


This is indeed a known issue. The exact cause is as follows:

Every train generates a list of track positions , the so-called "path",

when it rides along the track. The so-called "index" tells where on the

path the train is located at the moment. When a train moves, the index

is increased or decreased, and then the path is extended as needed to

cover the space the train occupies. Every wagon then independently

constructs its position and orientation from the train's path and index

and its own position in the train. Path elements that are too far away

from the train are deleted.

When a train has passed over a wrongly oriented switch, the path still

holds the "wrong" route. Unless you continue driving forward for another

10-20 nodes, which is when those wrong path items got deleted, the train

will continue on the old, "wrong" path backwards.

However, the path is invalidated and fully regenerated whenever a switch

is switched. This is why it works when you flip the switch twice.

In the current development version (the TSS branch) the issue is fixed.

Trains then regenerate their whole path when they reverse. (see also

this forum post


avatar From: Someone else
Mon, 03 Jul 2023 07:39:01 -0000

avatar Status Update
Tue, 12 Feb 2019 21:27:02 -0000
This bug was closed.