[0.16.38] Trains don't repath at chain signal anymore

[steinio]

Hi,

i'm used to see that trains waiting at chains signal for a while repath and try to find a new path.
This doesn't happen anymore:

chainsignal.PNG (845.49 KiB) Viewed 2191 times

Arrows are possible paths and circle is a free path...

Cu, steinio.

[Wolvereness]

This doesn't look like a bug to me. The path you are suggesting is open also appears to be longer. A train in the path will increase the calculated relative distance, but both paths here have a pending train anyway. The existence of a free block doesn't mean a train will take that path, it still will only take the path of the lowest relative distance.

[Jon8RFC]

I think this convenient type of behavior you're desiring from your screenshot no longer exists as of this fix in 0.16:
viewtopic.php?t=54042

I think that's the fix which which no longer allows simple "first available" path situations to exist dynamically via re-pathing, without aggressive circuit network setups. It may have been a late 0.15 fix (not the one linked) which removed the 2000 tile penalty, and that may have been the penalty which permitted the desirable behavior.

[steinio]

Hmm i recorded the expected behaviour in 0.16.39 vanilla but the file is 186MB in size.

A train waiting for the middle track reroutes as the top track gets free...
So maybe accidently fixed or not a bug...

factorio_2018-05-01_02-01-13.jpg (855.34 KiB) Viewed 2131 times

factorio_2018-05-01_02-01-18.jpg (847.75 KiB) Viewed 2131 times

[Loewchen]

It could be that the PF simply prefers the chosen route in the original case and does in fact reevaluate but with the same result. Without a simple test case showing the faulty behaviour there is not really anything to go on.

[Wolvereness]

Hmm i recorded the expected behaviour in 0.16.39 vanilla but the file is 186MB in size.

A train waiting for the middle track reroutes as the top track gets free...
So maybe accidently fixed or not a bug...

factorio_2018-05-01_02-01-13.jpg

factorio_2018-05-01_02-01-18.jpg

This example differs from the original in that all 3 tracks have the capacity for 2 trains. If you had a track with the capacity for only 1 train, and the others 2, and the track with lower capacity is shorter (mind the block sizes), a train will never go to the others. Trains don't prioritize forward progress, they prioritize distance, and this behavior is presumably intentional.