Factorio Forums

I'm getting to the point where some points on my rail network are a bit congested, so I'm moving to 4 tracks, two each way.

My T-junction design is giving me a bit of trouble. There are a lot of crossings and signals, and I believe I haven't caught all potential problems, especially in the middle area around the electric pole.

Before I start spending time upgrading my network, I'd like to make sure the design is solid, so this is a request for input.
How can I improve the design?
Is there a good alternative design that is actually deadlock free?

I would rather not make the junction any larger, as it is hard to fit in already, and all my current junctions are based on the distance between three large electric poles.

I think you need to decide what you need to get out of your intersection. It's basically a choose two scenario : every input can reach every output, no jamming (even if the pathfinder tries it's best), compact, high throughput.

Currently it looks like you're going for mostly for 1 and 3. See attached picture for a few suggestions on how to alter the current design to achieve 1 or 2 while still keeping the current look.

If you want all inputs to reach all outputs: add the blue connection and one of the green ones.
If you want to be REALLY sure that it won't jam (this is more of a theoretical exercise to be honest) don't add any new connections and remove the ones marked in gold. I'd recommend not doing this unless you actually encounter problems.

With regards to throughput the largest issue is the gigantic central block, marked in lavender (you can learn a lot from paint apparently), which blocks parallel trains from turning left at the same time. Other than that there is no blocking of unrelated lanes that I can see at the moment.

For the most part it should be fine, just remember to make the output blocks at least as long as the longest running train.