8 lane T junction

[Kewlhotrod]

for tracks, I cant figure this out. ideas?

[ratchetfreak]

Don't make all lanes connect up

find which directions are the most traveled and connect a proportionate amount of lanes in that direction.

There is no need for 4 lanes turning to the right when only 1 train goes there every 10 minutes.

[Cbrad24]

Well I mean.. This will work, but it won't let more than one train into the junction at a time :p

Needs to be wider I figured to even allow signalling, but yes as ratchet said you probably won't need that much throughput.

[RepairMan]

Chain Signals might help?

[Rockstar04]

The design Cbrad24 suggested also assumes bi-directional travel on all lines (No fault on Cbrad24, props for putting something together), but the OP may have also meant one way traffic on pairs or 4? We dont know, there isnt enough info in the first post to give a perfect answer.

[Kalanndok]

For the lines that may work, but looking at the signalling you just managed to put 24 rail-lines effectively through a ONE-LINE-BOTTLENECK since every train has to wait for the whole junction to be cleared.

Throuputwise you could have merged everything to one single line and then make the junction and then widen again to 8 lines.

[ltl king]

That looks like a major traffic jam. All those trains waiting to get into the switches.

[Kewlhotrod]

Well I mean.. This will work, but it won't let more than one train into the junction at a time :p

Needs to be wider I figured to even allow signalling, but yes as ratchet said you probably won't need that much throughput.

so that’s essentially what iv been experimenting with this hole time and basally it doesn't work very well, was hoping for a different design idea. I don't t think 8lane tjunction at all will work in-fact it just makes it a hell of alot worse from my testing, maybe i'll try splitting off 4 lanes from the train bus.

That looks like a major traffic jam. All those trains waiting to get into the switches.

[ltl king]

Well I mean.. This will work, but it won't let more than one train into the junction at a time :p

Needs to be wider I figured to even allow signalling, but yes as ratchet said you probably won't need that much throughput.

so that’s essentially what iv been experimenting with this hole time and basally it doesn't work very well, was hoping for a different design idea. I don't t think 8lane tjunction at all will work in-fact it just makes it a hell of alot worse from my testing, maybe i'll try splitting off 4 lanes from the train bus.

That looks like a major traffic jam. All those trains waiting to get into the switches.

Without seeing the whole map. The quickest solution I could come up with is to take 3-4 lines off the top and create a bypass for straight through.

Try this six way. I think it might work better than your 8 way.

-S-------------------II-----II--------------------------------S----------------------------II------------II----------S--
-S-----------------II--------II------------------------------S--------------------------II----------------II--------S--
-S---------------II------------II----------------------------S------------------------II--------------------II------S--
-S--------------II___________II---------------II------------------------II--------II_________________II---S--
-S---------------II----II-----------S---------------II_______________II----------------------------II---II-----S--
-S--------------------II--II---------S----------------II_____________II--------------------------II--II--------S--
______________________________________-- II_________II --
______________________________________-- --II______II - --
______________________________________-- -- --_____-- -- --
______________________________________ S_S_S_____S_S_S

May want the bottom 3 lines have a turnout to go up farther away from the intersection but like I say. Can't do that much with limited view and not psychically there testing.
If I could see the whole thing or even be able to play around with it. I could do something better.

[ltl king]

To improve on it. Have the bottom line east and west have a switch to go south and bypass the big intersection and not allow trains from those 2 lines into the intersection.
So it would go like
1-------------1
4-3--3--3--3--4
1----3--3----1
-1---3--3---1
-1---4--4---1
-------6------
Make sure the 2 outside north south lines are NOT connected to the big intersection.
Have them connect father down away from the big intersection.

[Cbrad24]

For the lines that may work, but looking at the signalling you just managed to put 24 rail-lines effectively through a ONE-LINE-BOTTLENECK since every train has to wait for the whole junction to be cleared.

Throuputwise you could have merged everything to one single line and then make the junction and then widen again to 8 lines.

Haha I know, but once I started working on it I realized the amount of space that was going to be required and figured it wasn't going to be worth it

[Kewlhotrod]

https://i.imgur.com/KoE7sBE.jpg?2

this is what iv tried doing, it works well and very little waiting on trains at the mo, although that being said, its only one entrance and one exit currently, we'll have to see if once iv gotten the northern mining bases up and running that it will be bottlenecked

cant figure out a better way without underground rail.

[Xeteth]

This is the one I made a while back, hope that helps.
Blueprint String found here

[bloodgiver]

That's a real beaut @Xeteth

You may call it overkill, but that's a sandbox game, right?
*Heavily inspired by "Junction of Doom" made by ColonelWill.
Sory in advance for bad editing, 3 screenshots into 1 in Paint

Click ME - This image is too large

[ssilk]

I have a factory with over 100 trains going around all the time, and I have only three or four places, where I needed to built a second rail.
Maybe - what I see very often in let's plays - two rails in each direction... might be useful...

But eight????????

Eight rails mean an 4 times higher risk of having a train, that in this moment is driving through the junction (and blocking it for other trains) instead of a simple 2 rails junction.

[MeduSalem]

I have a factory with over 100 trains going around all the time, and I have only three or four places, where I needed to built a second rail.
Maybe - what I see very often in let's plays - two rails in each direction... might be useful...

But eight????????

Eight rails mean an 4 times higher risk of having a train, that in this moment is driving through the junction (and blocking it for other trains) instead of a simple 2 rails junction.

True story. Anyone thinking logically will come to the conclusion that the approach is completely futile. On the contrary, eventually it will become a deathspiral:

The additional capacity each new train adds annihilates some of the throughput of all other trains thanks to the additional traffic jams they are causing in intersections up to the point where new trains don't outweigh the performance hit caused by them. The more tracks there are involved in an intersection the faster the point of diminishing return is reached. 8 tracks are therefore an effiency nightmare. A lot of the trains will be stuck just waiting for their paths to become free.

Refering to Xeteth's intersection above: Imaginine a train coming from South going on the outermost left track wanting to go to the outermost track heading West. It literally has to cross 14 tracks, thereby blocking ANY train wanting to go on any of those 14 paths involved. Up to 14 trains would have to wait for one single train to pass the intersection. After that depending on the route maybe all 13 of the trains will have to wait for the next in line maybe having a similar blocking effect on all others and so on. In that time new trains will arrive at the intersection and have to wait.

I wouldn't even wonder if the problem grows exponentially. It's just ridiculous and not worth the trouble.

2 or 4 tracks have a much better "amount of trains" to "throughput" ratio compared to 8.

So in particular there is no real point in having more than 2 tracks in parallel except if the tracks involved NEVER EVER cross with one another. Each intersection not avoided automatically reduces throughput to some degree: the more intersections, the less throughput.


And if I ever need 4 tracks in parallel I would do intersections similar to the little sketch I made below a year ago just for the sake of avoiding additional intersection traffic:

Train Intersection.png (20.59 KiB) Viewed 28170 times

I would minimize the crossing of the 3 tracks to a point to reduce the time of a train being in that particular block, increasing the throughput to the theoretical maximum.
Also the track switches for allowing a train to choose which of the two tracks to use in one direction would be further away from the intersection to basically "channel" the traffic flow long before the intersection is reached. They shouldn't be too close to the entrance of an intersection because if the intersection is busy then there is no room for the train to wait and it would block the track switch and thereby the parallel track as well. If they are too close to the exit of an intersection they might block the intersection if the train can't leave through the trackswitch. So if in doubt I would place them halfway between two intersections.
Considering that intersections should be at least 2 complete train lengths + length of the track switch apart from each other. Otherwise there would not be enough room for waiting trains and everything stalls.


And on a sidenote I really doubt that anyone needs that much throughput. I wouldn't even know what for because after sending a few dozen rockets to space I really get bored with a map and start over or take a break from the game as there isn't much else to do after reaching that stage of gameplay.

[bloodgiver]

@MeduSalem, @Ssilk,
I get Your point, I'm using similar design creating 4 (and more) lane junctions... However in my opinion if someone like "to go big" there's no need to bombard his idea to do so
If I make 20 lane T junction that's working - what is wrong with it?
Remember that Factorio map is infinite, so is one's imagination.

[MeduSalem]

@MeduSalem, @Ssilk,
I get Your point, I'm using similar design creating 4 (and more) lane junctions... However in my opinion if someone like "to go big" there's no need to bombard his idea to do so
If I make 20 lane T junction that's working - what is wrong with it?
Remember that Factorio map is infinite, so is one's imagination.

Well I don't want to bombard the idea of having 8 parallel tracks or something. If someone likes he may have a 1000 parallel tracks as well... as long as they don't interesect with one another.

It's just that even if the map is virtually unlimited and the game's slogan being "go big or go home" there is a practical limit to the throughput/efficiency involved with at-grade intersections. The more tracks there are the less efficient it becomes because the traffic jams caused by the intersection will actively cancel any hypothetical capacity gained by the additional tracks.

If there would be bridges/tunnels to avoid at-grade crossings then one could do however many parallel tracks one desires, but since there are no bridges or tunnels people have to face the fact that at-grade intersections impose a bottleneck that only becomes worse the more tracks are involved.

In real life railway companies and highway engineers invest millions to avoid at-grade intersections because of that reason. It is a problem that can't be solved by slapping another bunch of tracks or lanes next to the existing ones. It is a problem that can only be solved by building a bridge/tunnel and thereby create an interchange with grade-seperation.

[Arch666Angel]

After we have establish that this is for the lulz...

Brought to you by overly complex designs:

[vanatteveldt]

And if I ever need 4 tracks in parallel I would do intersections similar to the little sketch I made below a year ago just for the sake of avoiding additional intersection traffic:

Is there any loss of throughput in connecting the lower tracks going straight? It seems that if "most" trains are going straight, keeping the parallel tracks intact would help throughput, and I'm not sure how they would make the traffic blocks worse? (but my grasp of railroad throughput is pretty limited )