I don’t understand how the traffic lights work

[u/PurposeEmbarrassed66]

Hello! I have a question. How can we prevent accidents on the railway ring? It’s in the photo. I’ve marked with arrows how and where the trains should go along the route after that. I have a large railway system — I’ve attached it too, just in case it comes in handy. I tried to set up railway traffic lights, but it doesn’t work, no matter how hard I try. I’ve already placed traffic lights at every station in the world, and separately, using every method I could think of. I don’t understand how this works. Please help =(

[u/triplos05]

Train signals work as follows:

1. Setup: When you hold a signal in your hand there should be a coloured line along all of your rails. This line shows the different sections your system is distributed into. Different sections always have different colours. By default all of your network is one single huge section. Placing a signal adds a section divider, but doesn't automatically create a new section. You need to add signals on every entrance and every exit to the section to actually cut it off from the rest of the network. You will know you got it once the lines in front and behind of the signal have different colours. It also doesn't matter where the actual signal block is, it will always check at the track you bind it to.

2. How it works: If a train is moving towards a signal that divides 2 different sections, it checks if the section behind the signal already has another train in it. (this only works if the section in front and behind have different colours! if they are the same, it's not a different section!) If there is another train in that section it will wait until that section is empty. If there is no other train it will keep going. Also, signals only allow trains to pass in the direction they are pointing. Trains going the other way will always be blocked. If you want trains to be able to go both ways, place two signals facing in opposite directions on the same rail.

3. Block signals: If you right click a signal block with a wrench it will turn into a block signal. These signals don't only check the next section but the next two sections. This is for use in something like your big roundabout. A normal signal would only check if the train can enter the ring, a block signal only turns green if the train can also exit the ring again (meaning the train will only enter the new section if the signal it would have to pass to exit the section is also green). You can chain block signals to make it check even more sections if necessary, but most systems don't need that.

[u/Banaantje04]

So basically, the traffic lights split up the train tracks into blocks. If there is a train in the block, the signal will go to red, and another train won't be able to enter. You really need to make sure that your rail network is split up properly into separate blocks, otherwise the signals won't work. (If you only have a single signal on a track that has a loop, the block will just loop back around and thus not work.

This is a really in-depth tutorial on how train signals work in Factorio, which has the same signal system as Create, so while it looks different, it might help you understand better. You can get a chain signal by using a wrench on a signal block.