Help with intersection

[GSantiago]

After expanding my rail network for a bit i decided to upgrade from 2 to 4 lanes lines and I run into a problem with intersections.



The one in the left is the model I'm based this on. The thing is, I have no idea where to place the signals and I need some help with that.

[ratchetfreak]

There is a distinct lack of chain signals in the left one.

I suggest spacing things out more to get some more room.

Or only let right turning traffic from the right lane and left turning traffic from the left lane and put a switchover before the intersection

[ccik]

Honesty, this does not seem like a good idea.

I have never tried using 4-lane tracks before, but based on my expierence so far, my biggest issues with trains is not the straight tracks, but the intersections. And after seeing the trouble an intersection with a two lane track already makes, i can not imagine that this 4-lane track intersection would even work.
I see no way how you can arrange signals in a way that would allow more than two trains in the intersection at any given time, so completely rendering 2 of your 4 tracks useless. Also, the potential for trains blocking each other seems very high.
If we had bridges in the game, different story.

If you really need more than two lanes, i would suggest spacing things out a little bit, as mentioned before. Another thing i would try is to make designated tracks, starting off in the distance.
Example:
Looking at the track coming from the east. I would designate the rightmost 2 lanes running frome the east only for traffic going north, and maybe west. And these are the only connections i would make to these tracks so that it is impossible to head south on the rightmost 2 tracks. The other two lanes i would connect only to the south (or also west, depending on your factory setup.) Basically dedicated lines for each direction. With this approach, you can avoid some of the crossings, and make only ones necessary for a 90° crossing and the lanes diverging from 2 directions. Of course, you would need some connections between all the four lines, but i would place this far away from the intersection.
I hope this makes any sense to you. The same as in the post before, just explained in a different, probably more complicated way.


This is what i usually do in my factories: As soon as 2 tracks are not enough any more, in find an alternative route. I attempt to find some other way to route the traffic away from this intersection, and have a separate line somewhere else. For the example above: If i had most of the trains going east to north, i would try to find a shortcut by building rails moving in a nort-west and south-east direction, basically building diagonals in there. This useally helps me allevieate the need for more than two tracks.

But, if you or somebody is able to find a solution for your problem, i would be interested in the design.

[hitzu]

This design is utterly excessive and very complicated. I suspect that you don't really need every possible turn.
First of all you can allow to go straight and turn right from right lanes and keep left lanes for left turns only. Don't forget a good spacing.

[GSantiago]

So i did some changes on the intersection according to what you said and it ended up like this:



Is that signalling going to work?

[hitzu]

I would add chain signals between every crossing where it is possible. This would allow two or more trains pass simultaniously if their paths don't cross.

[ccik]

Apart from the mentioned chain signals, i can not spot any faults so far.

Just one improvment i'd consider:

Look at the track going to the west, the northernmost one. It combines two tracks, one from the nort, one from the east. A train is moving from the north, to the west. Shortly after, a train is moving from east to west, on the same track. Now, the east to west train stops dead center in the intersection, blocking most of it. You could prevent this with chain signals, keeping the center of the intersection clear for other traffic, but this would block the incoming east to west track. If you have enough space available, you could offset this intersection towards the west, creating two parallel tracks. One just for the trains coming from the north, one just for trains from the east. After one train lenght, you can merge these two tracks back. Thus, you created a waiting area for the outgoing trains, to clear up the rest of the intersection.

I made a crappy sketch of this. It shows only the most northwestern part of the crossing.




I don't know if it helps traffic flow, or if you really need it.

Just try your intersection, and we will see if it works. If you see the above happening, you can still upgrade the crossing later on.

[PiggyWhiskey]

ccik,
It's okay if that second train is blocking east->West. Because it is one too. Otherwise a train behind it would overtake. (i dont know a scenario when that would be needed)

The side buffer you suggested would only really be needed with lots of really long trains. But again, not quite needed as chain signals will prevent a train from entering the intersection if it can't leave.

Unless there is a massive backlog to the east and the next train in line is heading east with a couple of westbound trains behind it. But it would break again if there is more than 2/3 trains heading east.

Sorry for the rambling. On mobile so sorry for typos too

[ssilk]

That crossing is just too big. Big crossings tend to block. No matter what you do.

Currently I try to avoid to build 4-way intersections. Instead I build 3-way and only with maximum 2 rails. If I need more I try to put the other crossing as far away as possible, so that there is enough space between the crossings to make a buffer in case of a jam. The idea of ccik goes into the right direction.

[mazetar]

Check out the amazing builds by the factorio engineers!
Madzuri has an amazing collection of clever contraptions and intersections.

If you check out ColonelWill's stream here at 47 minutes inn you can see his 2 lane, 4 way intersection!
http://www.twitch.tv/colonelwill/v/21931589

I recommend looking into him and the other factorio engineers as they do quite awesome stuff
Will has what is probably the biggest functional rail network made in factorio, he knows a thing or two about trains and intersections