I could be wrong, but I don't think a bypass lane solves the root problem. Traffic that backs up to the bypass lane could still trigger a reroute through a station.

By spur stations, I mean dead-ends.

I think this is an issue that affects all builds that don't just use dead-end stations, in a way ...

That's not a real solution. When a train is stuck in traffic, the pathfinding penalty for the blocked path increases every tick. Eventually, that penalty will be greater than 2000, or 4000, or whatever finite number you choose.

Adding stations to increase the penalty is also clearly a kludge ...

A train that is stuck in traffic can re-route through an unrelated station as the pathfinding penalty from waiting grows every tick. This can cause unexpected deadlocks.

This doesn't happen often, but currently, the only way to guarantee no such behavior is to only use spur stations.

My suggestion ...

I understand what you are saying boskid, and I don't disagree. But I think there is more to it.

My proposal is: If any paths exist to a train station, but those stations are full, the train's status should be "destination full" instead of "no path."

The "no path" status would continue to act as ...

I made a video to illustrate the issue better. A module like this can't be copied and pasted without adding a flashing warning to the screen.

https://www.youtube.com/watch?v=uCQT3ehkY8c

0eNrlm9tu2zgQht9F13IhiucAvdjLfYbACGSb6wiVJVeS2w0Kv/tSkh0rzjCaIXJRbIECbmzp8z ...

No.

What you are asking for is to basically remove "no path". It is there to indicate that train was unable to reach a train stop that it was supposed to be able to reach, which will often show when some rails are destroyed, signals are incorrectly placed, rails are missing etc. Your case of ...

TL;DR
A train heading to "Plastic Input" will show a "no path" warning if all the stations on the local train network are at their train limit AND if there exists another "Plastic Input" station somewhere in a different train network. My suggestion is to not show that warning in this case.

What ...