Factorio Forums

This isn't a bug per se but it does seem to cause some problems.

Scenario: Player has x loading bays and a number of trains greater than x. There is enough room for the extra trains to queue before the loading bays so use a chain stop so train goes into next available bay:
The train picks a route and waits for it to become available, even after another bay has freed up. I can only assume this is because trains recalculate after passing signals or when something in its block, or an adjacent block, changes. Because the train is sat at the chain signal it is not recalculating.

A hacky workaround involving sort of turning a regular signal into a chain signal gets around the problem, but ideally trains waiting at a chain stop should also recalculate when the state of any signals at the end of any adjacent blocks change. Assuming that is the problem.

Note: There are a few bug reports on chain signals where a train passes one and then recalculates its path, often to one that is not available, so this needs to be considered.

If the train recalculated only while waiting at a chain signal it should solve both problems, I think.