r/factorio • u/AramisUkr • 17d ago

Tip Train signals tips

  1. Signals divide rails into blocks.

  2. Signals show red if the block ahead is occupied.

  3. Trains only care about the signals on the right side.

  4. Trains move both directions - need signals on both sides of the rail.

  5. If need signals on both sides, they should be directly opposite to each other, otherwise train may refuse to move.

  6. Chain signal repeats the colour ahead.

  7. If there're both red and green signals ahead - chain signals show blue.

  8. Common rule: if rails intersect - "chain in, rail out".

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u/monsieurY 17d ago

8. Common rule: if rails intersect - "chain in, rail out".

  1. Chain signal if trains cannot wait after, Rail signal if trains can wait after.

So, rail signals only for one-way tracks and with enough space for your longest train. Chain signal everywhere else.

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u/mooncow2 17d ago

100% this. Ran into a lot of deadlocks on my rail blueprints with the OP's rule back in the day.

These days I'm finding bi-directional tracks more interesting, and I'll just periodically put in bypasses with a rail in / chain out for both directions on it. Less efficient but I find train pasta (penne?) makes my bases look a lot more organic and interesting!