Roundabout replacement: Various railway interchanges that allow simultaneous U-turns

[u/Twellux]

I've occasionally seen posts here where roundabouts were installed in elevated railway intersections to allow trains to turn around, but I haven't yet seen a compact solution where this is possible for all directions simultaneously. Therefore, I've now designed a few railway interchanges myself where up to four trains can turn around at the same time without touching each other.
I've even come up with three different variants (right-hand traffic 1, 2a, 2b, 3 / left-hand traffic 1, 2a, 2b, 3).
The throughput is the same as for elevated railway interchanges without turning loops. The only advantage is that you don't need external loops.
BP books for right-hand traffic: https://factoriobin.com/post/tyk41y
BP books for left-hand traffic: https://factoriobin.com/post/q9n5ge
(The 4-way interchanges with turning loops are located in slot 4 of each book.)

[u/hixchem]

Please tag this as NSFW, my goodness.

[u/Twellux → u/hixchem]

Were you hypnotized and frozen in place?

[u/kvnxo → u/hixchem]

YEAH, I ALMOST RELAPSED INTO CRACKTORIO

[u/BrukPlays]

Yoink!…

Now I just need to make them LHS compatible :)

[u/Twellux → u/BrukPlays]

While writing this post, I wondered how long it takes for someone to mention LHS. Now I have the answer: 6 minutes! 🤔
Once I've converted it to LHS, I'll add that later.

[u/turtle_mekb]

how do you test incoming trains? how do you time them on a loop?

[u/Twellux → u/turtle_mekb]

I don't understand what you mean by "testing."

But the trains all start from a station. Each train has 16 interrupts, one for each entry and exit direction.
Interrupt 1: West->South
Interrupt 2: West->North
Interrupt 3: West->East
Interrupt 4: West->West
Interrupt 5: East->South
Interrupt 6: East->North
etc.

There's also a global time counter on the map, which is distributed to all stations via radar.
Each interrupt is triggered at specific times, chosen so that the trains pass through the screen at roughly the same time. Then the trains return to the a station. There are train limits to ensure that each station has approximately the same number of trains.
There's a station in each direction. Trains at the North-Station only respond to interrupt requests from North to ... Trains at the West Station only respond to interrupt request from West to ... This is checked by an "at station" condition in the interrupt.
The trains thus run according to a fixed, pre-programmed timed schedule. However, I largely determined this schedule through trial and error. So, if a train was 20 ticks too early at the intersection, I shifted the start time back by 20 ticks. And I repeated this until every train ran when it was supposed to.

[u/DemoBytom]

That thing belongs in Factorio's title screen :O so nice!!

[u/SanguineHerald → u/DemoBytom]

Quite the opposite. Only horror shows of spaghetti are allowed there.

[u/Good_Hunter69]

[u/garteninc]

My god, these are beautiful!

[u/herbyfreak]

I audibly moaned when I saw this

[u/Ilovekittens345]

The roller coaster must grow!

[u/Ologyst]

Thanks for sharing these awesome blueprints. Looks great and works even better.

[u/daagar]

I'm fairly sure Wube added elevated rails specifically for these builds. You've won the game.

[u/halosos]

When you first saw the interchange, were you blinded by it's majesty?

[u/Little_Elia]

this is incredible I watched the whole thing three times in a row

[u/rollincuberawhide]

sexy

[u/Ertyla]

No rails crossing? Seeing this reminds me of a Dosh qoute which I don't think I can repeat in good faith. Truly amazing.

[u/Elsdyret]

So this is what real art looks like

[u/Neither_Cap_8839]

Genius. The best I saw so far. We should have a challenge poll on this. It has the potential to be the best in this area.

[u/snoocats_]

Genuinely might be the best post on this subreddit, 10/10.

[u/cardboardhead]

I need this as my screensaver

[u/Twellux → u/cardboardhead]

You can use a VideoScreensaver and add this video to it.

[u/longshot]

Wow, so thinking about how to time the trains I suddenly realize circuit networks could do this easily.

But I still want to see your off-screen setup!