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I was wondering whether the design below is "correct" (i.e. deadlock free and throughput efficient). It wanted to make a double station (oil+coal in this case) on a line with links north and south, which allows trains to either turn around after the station or go straight. So I created two basic rail circles, with an extra pair of rails from the outer edges of the circles to allow station access.



Edit, fixed the esthetics (esthetically the right inner rail should be moved one to the right, but that was the existing track so I left it in place)

signals are chain on the circle "compass points" and going on to the circle, regular leaving the circle.

If your trains are short enough so they fit on the straight sections (e.g., no longer than 3 wagons in total (1 locomotive + 2 carriages)) I think this setup is deadlock free.
Your efficiency depends on the number of trains. If you have only one train for each of the two resources, you are fine. If you have multiple, then the second train could wait in front of the loop and block other train traffic.

Side note about the loops: If you make the exit of the loops symmetric (with two rail pieces fitting between the tracks), you will get a nice and even layout.

Yes, I currently have no "waiting area" - I guess that would mean either increasing the distance between the loops, or creating a separate waiting area before each of the loops or between the loops.

If you want to have room for more than 2 trains per station, is there a better setup for a waiting area than a N parallel tracks that all have converge to a central point and then branch out to the stations, with only chain signals between the waiting area and the stations?

ie

One possible deadlock:

Trains entering south, servicing one of the stations on the right and leaving north.


If enough trains enter from the south, the left part is filled up.

If the left part is filled up, the trains cannot leave the stations in order take the south loop for the north exit.

If the trains cannot leave the stations, they will block.


You could fix this by either ensuring that the trains will leave the side they enter. Or by only having one station on each side and using a chain signal for the free track so the trains can only enter if they can leave through an exit.

Good idea for a chain signal on the free track! That makes a lot of sense since you don't want to (ab)use it as a waiting area.

I would indeed always keep one set of tracks without station, the current station in the middle is an "inspection station", ie only used by my passenger train (FARL or single loc, depending on what I'm doing). If I slightly increase the distance between the loops (probably by one wagon-length or so), I could squeeze the inspection station in between the 'free tracks', and I could also add a single waiting location for each station (so two trains can use the same station without causing difficulty).