I made a thing. (4 way Overhead Rail intersection).

[Dogmai]

I really love theory crafting, I find it helps a lot managing my mental health and the depression.

I also have Dyspraxia, which gives me issues with motor skills, so I tend to gravitate towards building games (Minecraft, Factorio etc) or turn based games (Pokemon), because it just allows me to do things as I am able to do them. The Dyspraxia gets worse with stress, on good days you wouldn't notice it, except for me constantly dropping my keys and small things.

I am also Australian, so my rails are left-hand side driving.

I was thinking about how the overhead rails would affect the intersection designs, so this design can easily be flipped.

I started off sketching a possible intersection, the idea was that each possible outcome; left, straight, right - would not intersect other tracks, and there would be no U-turn available.

This is because if a U-turn is required, it should be placed before the intersection to keep train traffic outside of the intersection.

4way_sketch.jpg (209.34 KiB) Viewed 1227 times

I came up with that design, the right was the second go, followed by bottom then the top left.

Forgive my messy scribbling, I struggle with motor skills when stressed and life is like that at the moment.

I went to the FFF #377 and #378, and counted all the tiles to figure out the curves, and what would theoretically be possible.

I then went to Officeworks, and bought a book of 5mm graph paper, which worked out really well as the darker lines are 10mm, which is 2 tiles wide, the same as train tracks in Factorio. I sat down and started drawing in the curves only to realize after cutting them all out, that I had counted each 10mm square as one tile instead of two, so I had to do it all again.

This is the end result;

4way_large.jpg (447.69 KiB) Viewed 1227 times

I included a train for scale.

I am curious for opinions regarding this, there are many people in the community far more intelligent than I am, and I value your input.

Is this a decent design, can it be improved?

Can we make it smaller and more compact?

I wish to try and design 4 and 6 track intersections as well, but I thought I would start with the 2 track first.

I just blu-tacked paper onto the graph paper, so I could move it around whilst trying to figure out how compact I could make it.

I know it isn't much, but I am pretty proud of it.

For what it is worth guys, thank you for your Friday Facts, it is honestly something I constantly look forward to every week, this is the first time in a very long time that I have been excited for an upcoming game/expansion, the last one being Dark Reign in 1998, it is a nice feeling to have, thank you.

[Impatient]

How does this compare to a cloverleaf interchange?

https://en.wikipedia.org/wiki/Cloverleaf_interchange

[MeduSalem]

How does this compare to a cloverleaf interchange?

https://en.wikipedia.org/wiki/Cloverleaf_interchange

Windmills, Turbines, Pinavia interchanges and the likes are generally better for traffic because they don't have the "weaving" issue that classic clover-leafs have.

[gangan]

Nice job, that's some dedication for theory crafting I haven't seen in a while Also good to hear that it's helping your mental health.

On your intersection: I'm by far not a rail-expert, but with proper signal placing this should have a good throughput and high resistance to deadlocks. Plus it has a neat look, going to test this when 2.0 is finally released

[Illiander42]

How does this compare to a cloverleaf interchange?

https://en.wikipedia.org/wiki/Cloverleaf_interchange

Cloverleafs are terrible.

You want something topologically equivilent to a stack interchange. (https://en.wikipedia.org/wiki/Stack_interchange)

Also, useful mod for this: https://mods.factorio.com/mod/fake-new-rails

[Bizz Keryear]

How does this compare to a cloverleaf interchange?

https://en.wikipedia.org/wiki/Cloverleaf_interchange

Cloverleafs are terrible.

You want something topologically equivilent to a stack interchange. (https://en.wikipedia.org/wiki/Stack_interchange)

[…]

Ok, Stupid question: Why is the clover interchange so terrible?
Sidenote: The stack won't happen anytime soon in Factorio, it needs 4 levels of infrastructure.

[MeduSalem]

Ok, Stupid question: Why is the clover interchange so terrible?

Because of the "weaving"-issue, as described here in the Problems section of Cloverleafs wiki article:
https://en.wikipedia.org/wiki/Cloverlea ... e#Problems

Basically you still have traffic that is crossing on the same level: the traffic coming out from a loop crosses the traffic that wants to go into a loop.

That in return often causes traffic jams because the traffic has to queue up for the "weaving" phase.

But the issue gets even worse: Because you can hypothetically go around a cloverleaf forever the traffic jam caused by the weaving from 2 loops can propagate to all 4 loops in extreme cases. Therefore a cloverleaf design can even deadlock.

That is why in civil engineering no one builds any new clover leafs anymore because time (or better said increased traffic as to when they were built) has proven them to be troublesome. On the contrary, a lot of effort is being put into eliminating them where possible and replacing them by variants or other designs that don't have the issue.

In the city I live they also replaced a clover leaf for the same reasons several years ago. There it was very expensive because a 30m wide river is flowing in the median strip of one of the highway directions. They had to build bridges to cross the river as well to turn the intersection into cloverleaf-windmill hybrid. xD
But it had to be done because every morning and afternoon the former cloverleaf deadlocked like crazy, causing traffic jams in every of the 4 directions. Sometimes so far that it caused traffic jams even in the next closest intersections a few kilometers away.

Sidenote: The stack won't happen anytime soon in Factorio, it needs 4 levels of infrastructure.

Agreed. Real stacks will not happen in Factorio because more than 1 level of bridges will never be thing.

But Windmill/Turbine designs that are very similar to stacks can be made because they only require 1 level of bridges.

[Illiander42]

How does this compare to a cloverleaf interchange?

https://en.wikipedia.org/wiki/Cloverleaf_interchange

Cloverleafs are terrible.

You want something topologically equivilent to a stack interchange. (https://en.wikipedia.org/wiki/Stack_interchange)

[…]

Sidenote: The stack won't happen anytime soon in Factorio, it needs 4 levels of infrastructure.

Topological equivilence doesn't need 4 levels.

[mrvn]

Looks good. You have to be a bit careful where you place chain signals though to prevent deadlocks.

Naively using chain signals all across the intersection and since you are driving on the left side that means a train coming from the south going east will enter a chain signal at the first split off, be inside chain signals across the bridge and after splitting to the east and only leave the chain signals when merging into the east lane. That will block the follow up train for a long time. Not good.

Surely we can do better. The big north-to-east loop is certainly big enough to buffer a train or two (assuming your LCCL design). The north going part before that with the ramp and bridge should also be large enough for one train. So you can put full signals there. The north going part after the east split with the down ramp looks maybe large enough for a full train too. Lots of places to park a train without it being stuck on an split or merge. You might have to add a rail here or there to make it possible to place the signals far enough apart, hard to tell.

What possibly concerns me is the west-east direction. First you have the north split off, which is long enough to buffer a train. But then you have the south split off and the from north merge really close together. No way you can park a train there. I would try to move the split off to the left and the merge to the right a bit to create enough space between them for a 1 train buffer. Same for the east-west direction.


Now on to the 4 / 6 / 8 lane setups. Now you have to consider if you want lane changers or use ramps so the inner lanes can split and then cross the outer lane without an intersection. If every lane splits into a ramp and no ramp path you will have to widen the lane separation quite a bit. At least inside the intersection. On the other hand the new curves with less separation will reduce that compared to old rail curves.

Fun times ahead.

[mmmPI]

Is this a decent design, can it be improved?

It looks very good ! I'm not sure it's possible to "improve" the design without making it another design. I'm a big fan of cloverleaf despite all its flaws and to me an improvement would be to make it look like more a cloverleaf, but that might be counter productive depending on your definition of improvement. My second favourite would be the trumpet for the name, i think names are very important you should give it a name for it to have a chance ! Dogmai's ?

Can we make it smaller and more compact?

So this is more ideas, or observations, because i can't be sure that it all fit just from thinking of it , props to you!, it's the kind of thing where you move a thing but then it doesnt fit so you move another, and another, and you end up with another design.

The horizontal tracks "incoming" in the junction are not elevated, but there is an elevated segment above them, maybe inverting the level of those two would allow to have the "bad turn to the right" at ground level by going down instead of where you made the "good turn to the left", this one maybe fit before you have to go to ground level for the "bad turn to the right", at the elevated level, to merge in the vertical track still at the elevated level.

I wonder how "bad" it is considered if the junction require some entering tracks to be elevated already, that is similar to adding a ramp before some entrances of the junction. You loose the compactness of the junction itself as a square, but it occupy some extra space that would have been occupied anyway no ? And does it fit ? Again I can't tell before the game is released ^^

[mrvn]

I wonder how "bad" it is considered if the junction require some entering tracks to be elevated already, that is similar to adding a ramp before some entrances of the junction. You loose the compactness of the junction itself as a square, but it occupy some extra space that would have been occupied anyway no ? And does it fit ? Again I can't tell before the game is released ^^

You could have some convention saying N-S tracks are elevated and W-E tracks are ground level. That is if you are fine with building all your train stops horizontally or with ramps added for vertical stops.

[mmmPI]

You could have some convention saying N-S tracks are elevated and W-E tracks are ground level. That is if you are fine with building all your train stops horizontally or with ramps added for vertical stops.

You could also use the R key to have some vertical and some horizontal tracks incoming as elevated in alternating pattern for aesthetic purpose, or making a grid or adapating the terrain

[mrvn]

What a strange tale you weave.