On the capacity of trains

[henke37]

How does fluid and artillery wagons affect these calculations?

[Aeternus]

Once you have roboports, construction robots, and repair packs, could you use gates on an unsignaled rail system, and short trains (max length that won't destroy gates or rail cars when crashing at full speed), to prevent deadlocks and have trains queue by smashing into the gate or train ahead of them to avoid the braking distance problem? Is there any way to reliably tell if there is another train in an area without using circuit conditions from a rail signal?

Circuit connection to a gate and detecting if the gate is open. Gates on a railtrack are normally closed but automatically open for a train (or try to. Some of Bobs mods trains are so damn fast that they slam into a gate before it has time to cycle open).

But the problem then becomes that even if you slow a train to 0m/s, unless it logically stops as well (by arriving at a station, or by switching to manual and coming to a dead stop) the wagons won't open and you can't grab cargo from it with inserters.

There are several ways to slow a train to dead stop instantaneously, but the problem with all of them is that an automated train doesn't open up until it's at a scheduled stop.

[Hedning1390]

You can jump a station closer at the last minute and have a dead stop switch right before the closer stop. Too much effort though. A train following directly behind a train that is leaving won't be slowed down much by a slightly longer stopping distance. His breaking force is still what will determine how closely he will follow the train in front, and that won't change. The short time where the train in front has left and the second can accelerate freely is not significant.

[Selvek]

Once you have roboports, construction robots, and repair packs, could you use gates on an unsignaled rail system, and short trains (max length that won't destroy gates or rail cars when crashing at full speed), to prevent deadlocks and have trains queue by smashing into the gate or train ahead of them to avoid the braking distance problem? Is there any way to reliably tell if there is another train in an area without using circuit conditions from a rail signal?

Please, PLEASE give this a try and post a video of the carnage!

[DaveMcW]

Even if you don't abuse zero braking distance, removing signals allows trains to follow each other with no gaps. Of course keeping them at minimal distance from each other without crashing is a non-trivial problem.

[Hedning1390]

Even if you don't abuse zero braking distance, removing signals allows trains to follow each other with no gaps. Of course keeping them at minimal distance from each other without crashing is a non-trivial problem.

Unless you can say some way of preventing it that wouldn't defeat the entire purpose I think it is not just "non trivial". It's completely impossible.

[DaveMcW]

Use train stops to store trains.
Use gates to detect trains.
Use perfect timing to send a train from the station when the gate says it's safe.
The non-trivial part is you have to account for acceleration, which means the gate is far behind the train station and no branches are allowed between the gate and the station merge.

[Hedning1390]

You cannot insta-stop a train with stations if you at the same time use them to keep the train going forward. Insta-stopping would require the station order to go backwards. Since you cannot insta-stop trains you have to account for breaking time, which is exactly what signals do naturally, so you have gained nothing.

Can there be some use for such system? Maybe. Perhaps intersections can be made more efficient, but for the entire network I don't see it as a possibility, and can't signals just be forced green? Wouldn't that be a much easier solution: To have signals but also have circuits turning them green if they can follow closer?

[jcranmer]

How does fluid and artillery wagons affect these calculations?

Fluid and artillery wagons have the same values as regular cargo wagons for friction and braking force, although artillery wagons are 4 times heavier than regular cargo wagons or fluid wagons.

[mrvn]

You cannot insta-stop a train with stations if you at the same time use them to keep the train going forward. Insta-stopping would require the station order to go backwards. Since you cannot insta-stop trains you have to account for breaking time, which is exactly what signals do naturally, so you have gained nothing.

Can there be some use for such system? Maybe. Perhaps intersections can be made more efficient, but for the entire network I don't see it as a possibility, and can't signals just be forced green? Wouldn't that be a much easier solution: To have signals but also have circuits turning them green if they can follow closer?

I think the point was that you could avoid the braking distance between trains. You can pack them closer together if they are all going the same speed.

[Hedning1390]

I know what the point was. We were discussing how it could be accomplished and the difficulties actually making it work. I think with things running on a timer you could make such system work, but if you try to run it on detection I think you'll run into problems, as I explained.

[mrvn]

The problem I see is that you can't easily affect a trains speed. Without signals each train will accelerate till maximum and only slow down when it reaches breaking distance of its destination. You would have to plan each trains path in such a way that it is free of collisions all the way through.

Only non damaging way I can think of to affect the train speed would be train stops along the way and disabling them when the train is breaking distance from them at the desired speed. Train stops could also be used as signals to make trains stop before an intersection and such.