Trying to optimize roundabouts

[Anyone]

This is a roundabout I've optimized for 1-2 trains. What do you think? I would love to have some feedback!

[Mehve]

You may wish to double-check your signals. It's important to make sure that, if a train goes through a regular signal, there's nothing stopping it from continuing on through. Otherwise you run the risk of the train having to stop inside the roundabout and clogging things up. A general rule of thumb for roundabouts is that the only regular signals should be the very last signal on each path out. Everything else, you'll most likely want as a chain signal, which guarantees that a train will never enter the roundabout without a clear path out.

The red circles indicate signals where the train could pass potentially pass through, but immediately be forced to stop just a couple meters ahead if the next signal, effectively stopping the train inside the roundabout. You could probably just erase them entirely, but at least convert them to chain signals.

The green circles are entry points for the roundabout, they should DEFINITELY be chain signals. As-is, the very first block entered might be empty, but the next could be occupied, leading to a situation where the train comes to a stop inside the roundabout.

Having said all that, the basic design is solid enough. The only potential weakness might be the inability to handle more than one left-turning train at a time, but that still fits within your design goals. Make sure the first block of track after each exit point is long enough to fully hold the longest train that you expect to use the roundabout.

[aober93]

So 2 trains can turn right at the same time? Whats the point?

The way i see it, no 2 trains can enter the junction at the same time, except if one of them turns right and picked the bypass. But the issue is that you need chain signals, but if you add them, even the train on the bypass blocks the whole junction, so you have gained nothing and im back at my question. You need chain signals but they destroy the idea... In essence this design is flawed.

This setup is really only optimized for 1 train only, what you call it.

[Grossen]

As soon as i learned how to make roundabout train system i noticed they get a lot of hate for their impact on performance in larger factories and they are also highly inefficient in some cases but allow you greater flexibility when making stations. And let's not forget 1-headed trains.

[aober93]

It doesnt matter ,its what you are trying to achieve.

[Mehve]

So 2 trains can turn right at the same time? Whats the point?

The way i see it, no 2 trains can enter the junction at the same time, except if one of them turns right and picked the bypass. But the issue is that you need chain signals, but if you add them, even the train on the bypass blocks the whole junction, so you have gained nothing and im back at my question. You need chain signals but they destroy the idea... In essence this design is flawed.

This setup is really only optimized for 1 train only, what you call it.

Is this roundabout capable of:

4 simultaneous right-turning trains? Check.
2 simultaneous straight-thru trains? Check.
1 straight-thru train AND 1 or 2 right-turning trains? Check.
1 right turning train AND 1 left-turning or U-turning train?
Check.

Sounds like a 1-2 train roundabout to me.

[mrvn]

So 2 trains can turn right at the same time? Whats the point?

The way i see it, no 2 trains can enter the junction at the same time, except if one of them turns right and picked the bypass. But the issue is that you need chain signals, but if you add them, even the train on the bypass blocks the whole junction, so you have gained nothing and im back at my question. You need chain signals but they destroy the idea... In essence this design is flawed.

This setup is really only optimized for 1 train only, what you call it.

Are you maybe misunderstanding how chain signals work? Chain signals are green if all the signals directly behind it are green. They turn yellow when a train reserves the block they control. They turn red when a train enters the block they control or all the signals directly behind it are red. But they also turn blue when only some of the signals directly behind it are green.

A train can pass a chain signal if none of the chain signals or the next signal along it's path is red or yellow. So a train entering a junction will turn the signals along it's path yellow and then red. But the other chain signals in the junction will only become blue.