Railway Turn

[Kevinski]

Hello
altough i am new to the forum i have factorio for quite a while now and i am currently playing with the shadowmod pack (+ some extras), so building up a base with bob's mods is really a pain in the a** =)
but i just wanted to show a way of building a turning point for trains in a double rail scenario without actually crossing the tracks.

So, here is the whole thing:

Turn

screenshot10496013.jpg (98.98 KiB) Viewed 25632 times

then there is a one sided version which i use for my station exits so that leaving trains can always pick the fastest way back and also that incoming trains dont have to follow the track all the way around the base.

one side

screenshot10497575.jpg (155.41 KiB) Viewed 25632 times

and finaly an example:
you see my copper Drop(still building it up, wasnt necessary up until now)
above that(not in the picture) there is the Refuel Station with four Lanes(for Smarttrains mod)
and above the refuel and bellow the copper station there is a one sided version allowing all the trains to pick the best route.

example

screenshot10512609.jpg (298.43 KiB) Viewed 25632 times

so i hope this can help others and i would appreciate critique on wether this is a go solution to avoid crossing the tracks(or building roundabouts)

[vanatteveldt]

This takes as much space (and about as much rail) as two roundabouts in sequence. Do you think there is a throughput advantage over using a (double) roundabout?

[Kevinski]

This takes as much space (and about as much rail) as two roundabouts in sequence. Do you think there is a throughput advantage over using a (double) roundabout?

i haven't thought about actual throughput as of yet though i can imagine that this allows the trains to change direction with reasonable speed.

The main idea behind this setup was actually to prevent a deadlock by blocking the roundabout and to prevent rails from crossing each other in any other way.
I must admit that the idea came from my time spend in cities:skylines while trying to build efficient highway routes(it workes there because the cars prefer driving on the right site and therefore others can turn into the highway on the left side uninhibited)

of course i also know that it takes more space than a normal roundabout especially in length but to be honest space wasn't a concern as the base is already huge and im not even building modules yet(also i kind of like belts so that takes space^^)

[SpeedDaemon]

Not providing trains a place to turn around tends to make them use stations for that purpose, which is generally bad, as they'll end up sitting around behind a train that's stopped there (devs, can we pleeeease have passing a station without stopping impose a big pathing penalty?).

Also, Kevinski, it looks like you're using chain signals at the platform exits in your last pic. This will actually hurt throughput, since trains will sit at the platform until the previous train has completely exited onto the main line AND cleared the first block on the mainline. In this case, you probably want them following each other out as closely as possible, so changing those to normal signals would be better. (I'd also add another signal immediately after the last platform joins the exit track, and another halfway between there and the signal at the main line)

[Kalanndok]

Not providing trains a place to turn around tends to make them use stations for that purpose, which is generally bad, as they'll end up sitting around behind a train that's stopped there (devs, can we pleeeease have passing a station without stopping impose a big pathing penalty?).

There's no need for that. Just set a chain signal in front of switch at the ENTRANCE to the station's line and a normal rail signal after that switch. That will prevent any passing train to enter the station if it is currently occupied.

[ccik]

I can see what you are going for, but i don't think that this solution is a huge improvement.

First, you still need to cross tracks, you just do it at another place.

In your picture with the station, imagine the following situation:

A train arriving from the south wants to go left towards the station. It has to cross the opposite track at some point. With regular junctions, the train would have to cross this track. With your design, the train leaves his track and merges with the north-south lane for a short time, before splitting up.
But for both cases, the same happens when other traffic is present at the line. A train moving in the opposite direction has always a chance to arrive at the junction/merge point when the incoming train is there.
The one advantage your design has is that shorter trains can wait inside the loop without blocking the main line, which is not possible for junctions.

I hope this makes sense. You still have your crossing in your design, just at different place. The only way to avoid track crossings would be to build bridges, so i hope this feature gets added at some point.

For my games, I always go with three-way junctions, carefully placed chain signals, and never really had any issues with deadlocks or trains

[Antaios]

The main idea behind this setup was actually to prevent a deadlock by blocking the roundabout and to prevent rails from crossing each other in any other way.

Trouble is, this is just as likely to lock up as a double roundabout, and is probably slower than just having trains cross the tracks.

All it takes is a train in the loop above the station which would be entering the station from the south, plus a train in the loop below the station, which would be exiting the station heading north. If the lines are busy, so there's about two trains on either side, the loops lock up.

For this particular station, I think the best solution is to either have a junction, or a roundabout at the actual exit/entrance.
That allows trains to exit and enter from either direction, and trains related to the station won't want to U-turn anywhere.

If there'll be no more than about 5 trains on the line, or only one train using the station, then it's not a problem either. (although when combined with the station above, might be, I can't see that one).