So, I have 2 train routes for exports, highlighted for visibility:
- A cement train that runs between the red line (at the end of which is a loading station for cement) and the customs house at the far end of the green line
- A gravel train that runs from the aggregate loading station at the end of the blue line to the same customs house
Here's the behavior I want:
- When returning from the green route, a train has right-of-way to return to its loading station
- If a train arrives at the intersection from the red or blue route, it should proceed only if there is no train on the green line; otherwise, it should wait until the green line is clear
I'm not entirely sure how semaphores work and no combination of them seems to do the trick. I get trains unable to return from the customs house, trains colliding, or trains forever deadlocked at the junction. I've watched/read like 3 different tutorials and I'm still not sure what I'm supposed to do.
Make parallel lines going in opposite directions instead of trying to have a bidirectional rail. IIRC workers and resources has similar train signalling to factorio, which means it is possible to make a bidirectional rail work, but it will never be a good solution.
IIRC it has chain signals, right? Where it is essentially a "do not pass this point unless you can fully clear the next segment" signal? If so, use those entering into the bidirectional segment and one pair of them within it, and a normal signal going into the deadend terminals that aren't the customs house. That should logically work out to "you are not allowed to leave the deadend unless the other train is in its deadend", although it's still not a good solution and would 100% break if the customs house has its own signal in which case you need a bypass so a train can sit there and wait in a position where it can't block the customs house exit.
Seriously just use two separate rails for inbound and outbound traffic though. Build them in a way they can extend to form a backbone later, and have the stations be side paths with dedicated one-way on and off ramps. It'll be a more robust and easy to work with solution that scales better and saves you so much grief.
Unfortunately a bidirectional rail is a necessary evil in the case of the customs house because a train has to leave it the way came in (it's at the edge of the buildable map so you can't make a loop)
It's been a long time since I played workers and resources, but I know I used two separate rails in general. There you'd just have them joining together but still being one-way each, with signals to stop the incoming train before the point where they join and to prevent the returning train from trying to go down that line. Am I correct in remembering that there are "do not go this way down this line" signs/signals, rather than that being an intrinsic property of signals themselves?
There are directional signals, yeah.