Train does not use free path [solved]

[fly]

I have a railroad system that was running for a while but then I noticed train stuck. So I created the simplest possible replica in sandbox and tried to replicate and fix the problem.
Here is what I have:
Black train runs between station 1 (St1) and station out of the image where green arrow shows.
Blue train runs between station 2 (St2) and station that is far to the left.
Black train usually chose path A, but if it's blocked by blue, then it goes via B.
Most of the time this is working without problems. But, in the rare case, when black train starts from station St1 and choses path A, and then in a moment blue train starts from St2 it blocks the path A and path B becomes free. But black train still wants to make it via A and the whole thing stops.
The questions are: Am I doing something wrong? Why doesn't it recalculate its path on blue signal? Is it possible to fix this with just signals, without changing the tracks?
Attached are screenshot and save file.

rail problem.jpg (817.49 KiB) Viewed 1703 times

[Greybeard_LXI]

Path B is a very long path. Version 15.0 changed rail calculations to make stations real long:

Train station adds 2000 tiles penalty when path finding, so trains try to avoid stations not related to their path.

Removing station 2 or removing a tile behind the blue train will cause the black train to take path B.

It sounds like the path finding does not expect a blocked track to stay blocked for that long.

[fly]

Oh, I see. Thanks! Hope this will be added to the wiki soon.
For my problem - I just added dummy station on A path to balance them and this seems to be working, more or less, as I want.