Ro-Ro station that does not allow through traffic

[aaargha]

I've designed a pretty simple setup that can make sure that trains that are not stopping at a station won't be able to travel through it. Please note that trains can still attempt to path through the station (at a heavy penalty), they just won't be able to actually travel along that path. In short, while it should help, it is no silver bullet for strange path-finding.

The setup uses a "train sensor", a circuit controlled rail signal and a chain signal to do its thing.

Core setup

basic.png (193.76 KiB) Viewed 5510 times

Core setup BP

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From that core setup we can, for example, design an outpost that only allows trains actually visiting it to use it:

Outpost

outpost.png (1.03 MiB) Viewed 5510 times

Or we can make sure that trains that use a station complex to turn around use the designated bypass-lane instead of the stations:

Stacker + stations

stacker+stations.png (1.75 MiB) Viewed 5510 times

I've not really looked at other applications but it's probably possible to combine this with disabling stations to make something interesting.

[impetus maximus]

very cleaver. i'll have to try this out.
question... does the rail have to cross? would you be able to put the signals 'in line'?

[mrvn]

Doesn't that deadlock when a train does path through the station? It will be stuck forever on the chain signal waiting for the station signal to turn green.

My solution to through traffic is to make all stations as a loop with their exit before their entry. That way pathing through the station will always be longer than skipping it and will never be taken. On a 2 tracks system that means though that you can only enter the station from one track. From the other side you have to do a 180° turn to get on the other track. Doing a backward loop entry for the other track is too complex to be worth it.

[impetus maximus]

when a train occupies that block it will turn the cross signal orange, then red (no green signal) which will turn the other signal green.

[aaargha]

very cleaver. i'll have to try this out.
question... does the rail have to cross? would you be able to put the signals 'in line'?

I don't think placing the rail signals "in line" will work, at least I can't think of a way to make it work at the moment. The reason for putting it off to the side is that it allows us to see if the block is free or not without affecting the input signals. It would have to be placed before the closed signal so that it will actually notice the train. But, at the same time, we have to make sure that the chain signal never turns green as that would allow stray trains to get to the station.

It's probably possible to replace the "train sensor" with some circuitry connected to the train stop instead but I don't really see a clear benefit of doing it that way.

Doesn't that deadlock when a train does path through the station? It will be stuck forever on the chain signal waiting for the station signal to turn green.

That depends a bit on the situation. In the examples provided I've made sure that the trains always have a "way out" that does not go through the blocking station. There is still a risk of that being the shortest path which, as you say, would deadlock that train and those stuck behind it. While that is, obviously, far from ideal, it might be used as a clear indicator that something is wrong with the train system as the penalty for going through such a station is going to be at least 3k tiles, probably upwards of 4k.

While plonking this design down everywhere might be problematic, unless you want your system to fail noticeable and early so you can fix it. I think it may be useful for some more specialised cases, for example some circuit setups that do not handle stray trains gracefully.

My solution to through traffic is to make all stations as a loop with their exit before their entry. That way pathing through the station will always be longer than skipping it and will never be taken. On a 2 tracks system that means though that you can only enter the station from one track. From the other side you have to do a 180° turn to get on the other track. Doing a backward loop entry for the other track is too complex to be worth it.

That is a really interesting solution, even if it's a bit limited to be practical IMO.

[mrvn]

My solution to through traffic is to make all stations as a loop with their exit before their entry. That way pathing through the station will always be longer than skipping it and will never be taken. On a 2 tracks system that means though that you can only enter the station from one track. From the other side you have to do a 180° turn to get on the other track. Doing a backward loop entry for the other track is too complex to be worth it.

That is a really interesting solution, even if it's a bit limited to be practical IMO.

It's the same station layout as you have except only accessible from one track. One of your entries is after the exit, the other, the one crossing tracks, before. So if you remove the crossing tracks you have my design and a foolproof solution.

[Zijkhal]

I've experimented with something similar, but I did not think to put chain signals all the way to the entry. The problem with that was that trains did not really seem to care about the red signal in the test environment...

Next I could thing of is to have space for two trains in the dedicated station line (so the next train can line up while the previous is stopped at the station), and only enable the signal after the station if there is a train pulled up behind, this way making sure there always is one train at the station. And since there is a penalty for going through a train stop, and also for any trains along the path the train wants to take, the longer the train has been waiting there, the higher that penalty, in theory there should be a greater chance that no trains will try to path through the station, and even if it did, it would release the train at the station, and would have to wait until a new train pulls up behind, but it would not deadlock.