Does anybody have any good overhead 4-way train intersections?

[Liwet]

I try to make one but there's no room for signaling or supports. So I move everything one tile out. Do the same thing. Still not enough room.

How wide does the smallest intersection have to be?

[malogoss]

This one is so simple, it's actually genius.
youtube.com/watch?v=NQYjSMcB1l4

[Liwet]

I'm looking for an overhead-only intersection.

[knighttemplar1960]

Originally posted by malogoss:

This one is so simple, it's actually genius.
youtube.com/watch?v=NQYjSMcB1l4

I started with a similar set up but there were still places that train traffic would slow down too much, so I greatly expanded the size of the intersection and went with true cloverleaves.

Originally posted by Liwet:

I'm looking for an overhead-only intersection.

Pure over head is going to have signalling issues. Any reason you want that specifically?

[Chindraba]

Originally posted by Liwet:

I'm looking for an overhead-only intersection.

An overhead-only intersection is going to be exactly the same as a ground-level one for performance. If there is a need, a really hard-to-avoid need, for the entire intersection to be overhead, then it must be so, but I'd not want to make one with all the extra costs while sacrificing the performance benefits of having one on both levels.

[malogoss]

Cloverleaf is an easy but horrible design at the same time. Pretty much what a main bus is to base design.

If you look at 0:20 in the video, you'll see a train (A) coming from the south heading to the east. That train stops and yields to a train coming from the north heading east. That's a wait that is unavoidable. Tracks have to merge sooner or later and when they do, trains sometimes wait.

It's possible to outperform the video design only because train A, while waiting, happens to block the traffic coming from the south. That's a design flaw that can easily be corrected, the waiting section is just half a wagon too short for the whole train to fit in it and let south traffic pass. Stretch rail sections by half a wagon length and the whole intersection becomes a lot better in terms of throughput.

Unless your first design had other flaws, cloverleaves are not better. All they do is force you, by design, to stretch all the waiting sections by a lot, and I mean by A LOT. It pretty much guarantees enough room for any medium size train to wait while not blocking anything with its tail end. Use huge trains and the problem happens again, cloverleaf or not.

The 270° turn detours imposed by a cloverleaf design are painful to look at. The footprint of the whole thing is also just silly. But if you can forget about it by looking away, sure, they'll get the job done and your trains get to travel scenic detours in the process. Too bad they don't carry passengers.

[malogoss]

There's a stage in the game, on Fulgora, where you'd expect most intersections to be 100% elevated rails. This could be why OP needs them.

[Chindraba]

Here's a RHT/LHD (U.S. style) 4-way in elevated rails.

https://steamcommunity.com/sharedfiles/filedetails/?id=3382871156

You can expect that performance is on par with other simple 4-way junctions - low, but normal and acceptable for non-megabase use.

[RiO]

Originally posted by malogoss:

There's a stage in the game, on Fulgora, where you'd expect most intersections to be 100% elevated rails. This could be why OP needs them.

And to add: if that is the intended use, then with the throughput you'd need out of them at that stage of the game, a basic roundabout with 4-way exits will suffice.

[knighttemplar1960]

Originally posted by malogoss:

Cloverleaf is an easy but horrible design at the same time. Pretty much what a main bus is to base design.

If you look at 0:20 in the video, you'll see a train (A) coming from the south heading to the east. That train stops and yields to a train coming from the north heading east. That's a wait that is unavoidable. Tracks have to merge sooner or later and when they do, trains sometimes wait.

It's possible to outperform the video design only because train A, while waiting, happens to block the traffic coming from the south. That's a design flaw that can easily be corrected, the waiting section is just half a wagon too short for the whole train to fit in it and let south traffic pass. Stretch rail sections by half a wagon length and the whole intersection becomes a lot better in terms of throughput.

Unless your first design had other flaws, cloverleaves are not better. All they do is force you, by design, to stretch all the waiting sections by a lot, and I mean by A LOT. It pretty much guarantees enough room for any medium size train to wait while not blocking anything with its tail end. Use huge trains and the problem happens again, cloverleaf or not.

The 270° turn detours imposed by a cloverleaf design are painful to look at. The footprint of the whole thing is also just silly. But if you can forget about it by looking away, sure, they'll get the job done and your trains get to travel scenic detours in the process. Too bad they don't carry passengers.

Strange. Most interstate intersections in the USA are clover leaf or partial clover leaf designs. I was never a civil engineer but there has to be a reason that they are in such heavy use. As far as in game they work well (and they also work quite well in Open TTD where I have been using them for years) and they certainly work better than roundabouts or circuses.

Their performance is fine. The only issue is the amount of room they take but I have never even used 1% of the map so that isn't a problem.

Main bus is not a bad organizational tool (though there are admittedly better ways) and Space Age has made it better with green belts and stack inserters.

[malogoss]

Originally posted by knighttemplar1960:

Strange. Most interstate intersections in the USA are clover leaf or partial clover leaf designs. (...)

To me at least, there's nothing strange about opting to build an intersection at the lowest possible cost ($) in real life. If it worked with just a basic ground level 4 way crossing plus 4 stop signs, that would be it.

[Liwet]

I need it for Fulgora. Sometimes you have a crossing but no islands available. I'll deal with congestion when it becomes an issue. For now the issue I'm trying to solve is to have trains coming from any direction able to go to any other direction.

[Chindraba]

Originally posted by knighttemplar1960:

Strange. Most interstate intersections in the USA are clover leaf or partial clover leaf designs.

And the international engineering community gives the US a D+ grade on its road status.
Cloverleafs are a good idea for moderate density traffic - when done correctly with enough space used. At volume, however, they under-perform, cause backups and increase accident rates. While it's a very expensive process, the US is working, in some places, to replace/redesign the cloverleaf with directional interchanges, or with flyovers and tunnels where needed by space limitations.

Being better than a bad thing, a simple 4-way, does not make cloverleafs the best thing.

Being less evil than the average convict does not make you a saint.

[knighttemplar1960]

Originally posted by Chindraba:

Originally posted by knighttemplar1960:

Strange. Most interstate intersections in the USA are clover leaf or partial clover leaf designs.

And the international engineering community gives the US a D+ grade on its road status.
Cloverleafs are a good idea for moderate density traffic - when done correctly with enough space used. At volume, however, they under-perform, cause backups and increase accident rates. While it's a very expensive process, the US is working, in some places, to replace/redesign the cloverleaf with directional interchanges, or with flyovers and tunnels where needed by space limitations.

Being better than a bad thing, a simple 4-way, does not make cloverleafs the best thing.

Being less evil than the average convict does not make you a saint.

Strange comparison jumping from a moderate traffic solution to criminal activity. Having done logistics and accident investigations IRL I can tell you the causes of the majority of collisions in the USA is not intersection design. Its driver inattention and lack of training. Distracted driving is now the leading cause of vehicle collisions. Displacing drunk driving from the top spot. The first cause that isn't strictly driver related is vehicle maintenance at number 10.

Since trains in Factorio are automated, and quality rails have no real effect on intersections, the only thing your intersection has to do is keep the traffic flowing. Since my trains are spread around the base instead of all concentrated in one location and I have yet to exceed 100 trains on any single planet the clover leaf intersection works just fine at keeping train traffic moving.

The clover leaf intersections with paired one way rails all ready handle traffic better than than 4 lanes using round abouts did in 1.1. Since all off planet science packs will be dropped directly to the lab set up from space, low density structures stack to 50 instead of 10, rocket control units have been replaced by blue circuits, and fluids are better transported long distance by pipes instead of fluid wagons my train density for a 5k SPM megabase will be significantly less than it was for 1.1 and elevated rails solve the congestion problems just by eliminating crossings.

I won't need an intersection that can handle 100 trains per minute when I'll be running about 200 trains total.

@OP How many scrap trains are you running? Dedicated 2 way rails are likely enough to move scrap to one central recycling area at least until you can pave the oil oceans.

[MASTAXPLODER]

https://steamcommunity.com/sharedfiles/filedetails/?id=3353868238

[SpeedDaemon]

I'm also not a civil engineer, but I'm guessing cloverleaf intersections became popular due to providing intersection-less direct connections, while only needing a single short bridge section - the rest can be built on the ground or embankments. So: cheap, and fewer problems with icing in the winter.

Their major flaw is that they merge before split - the incoming leaf joins and adds extra traffic right as the departing traffic is trying to occupy that same space to exit.