Max size of a N:M waiting bay - stations crossing?

[mrvn]

I want to build a HUGE train station that can still be serviced by a single line going in and one going out. This is an exchange depo so items are unloaded from one train and loaded onto another. I think using cars as buffer chests is best there but feel free to suggest other things. Trains are to be loaded and unloaded on both sides with 6 stack inserters each (12 total and consider the bonuses).

For simplicity and to maximize the number of trains I'm going with really short 1 wagon trains, always full or empty. The goal is to maximize the number of trains per minute passing through. The station is to have N waiting bays and M stations for loading and unloading. M should be even to have the same number of loading and unloading stops.

And now comes the challenge:

What should N and M be and how is the station layout to get trains driving in full speed on one end and out full speed at the other with minimum sane distance between them. I'm declaring the minimum sane distance to have no more than one signal per train length on the main track.

Alternative: Have one track for items coming in and empty wagons going out and one track for empty wagons coming in and items going out. But I think the crossings needed will make things slower.

[Shokubai]

I created something similar though it essentially is 2 depots side by side. Think of it like two letter "U" side by side.Both depot enter on the top left immediately into a SW facing stacker. The stacker feeds sets of U loop stations and each exits up the Right side of the U. Belts from the output of each station goes immediately to the inputs in the other U. This way I can easily align Iron-Iron, Copper-Copper, etc... The shape works very well because it is easy to add to the stacker or add loop-stations to the bottom.

In my case I use this as an ore depot. I drop 1-2 trains and pickup with 2-8 trains. I have 3 of these currently on the far ends of my map. I long haul with larger trains to my smelting factory.

This is an example of the "U" from an earlier version of my game available to me here at work. This one is E-W facing and has a small FARL station on the one side but the design is basically the same. You could easily imagine a second of these adjacent so belts could run parallel to the station track from drop off to pickup.

2017-05-22 07_57_34-Factorio 0.15.12.png (30.24 KiB) Viewed 3108 times

[vanatteveldt]

Are you fixed on double header trains? Because with single header LCL trains you could avoid the crossing by meshing two forks (if that makes sense) like so: (although the space overhead for the two locs and the turns makes LCCL more attractive I think...)



Trains would come in / leave from the top right and bottom left, you can make stackers in the horizontal area between the two lines at the top and bottom.

[Shokubai]

... with single header LCL trains you could avoid the crossing by meshing two forks (if that makes sense) like so: (although the space overhead for the two locs and the turns makes LCCL more attractive I think...)

This is a really interesting idea though It seems odd you would transfer something between identically sized trains..

[vanatteveldt]

Not the OP, but it might makes sense if you want to create an n:m setup (say multiple mining outpost and multiple other smelters) without having waiting bays at the end point: each smelter/outpost is serviced by a single train (or 2 trains, but not 10) and the exchange station is the multiplexer. The real advantage is that you can add or remove supply sources (think mining outpost) without the consumer being affected at all. It basically isolates producer -> exchanger from exchanger -> consumer.

(there was a long thread along similar lines a while ago, but can't find the link quickly)

[mrvn]

I created something similar though it essentially is 2 depots side by side. Think of it like two letter "U" side by side.Both depot enter on the top left immediately into a SW facing stacker. The stacker feeds sets of U loop stations and each exits up the Right side of the U. Belts from the output of each station goes immediately to the inputs in the other U. This way I can easily align Iron-Iron, Copper-Copper, etc... The shape works very well because it is easy to add to the stacker or add loop-stations to the bottom.

In my case I use this as an ore depot. I drop 1-2 trains and pickup with 2-8 trains. I have 3 of these currently on the far ends of my map. I long haul with larger trains to my smelting factory.

This is an example of the "U" from an earlier version of my game available to me here at work. This one is E-W facing and has a small FARL station on the one side but the design is basically the same. You could easily imagine a second of these adjacent so belts could run parallel to the station track from drop off to pickup.

2017-05-22 07_57_34-Factorio 0.15.12.png

That's basically what I have and want to scale up. I currently have one iron ore unloading and one iron ore loading stop and that isn't enough anymore. So I think I want one larger depo for iron ore and copper ore with multiple loading/unloading stops. I don't like belts as they slow down the inserters. I use cars instead. inserter->car->inserter fits exactly between two tracks.

[mrvn]

Are you fixed on double header trains? Because with single header LCL trains you could avoid the crossing by meshing two forks (if that makes sense) like so: (although the space overhead for the two locs and the turns makes LCCL more attractive I think...)



Trains would come in / leave from the top right and bottom left, you can make stackers in the horizontal area between the two lines at the top and bottom.

Yes, you avoid the crossing between supply and consumer train. But now the trains arriving and leaving are crossing. Not sure which is better.

I think from a crossing standpoint it evens out but a bidirectional train has to pull an extra engine around making it slower. I think the first step is to design a race track and measure the maximum number of trains you can put on a single track. I'm thinking something like this:

Code: Select all

     /------A--B------\
/---<-------A--B------->---\
|    \------A--B------/    |
\_________________________/

All trains going to stops A and B with 0 time passed. Then scale up the number of parallel lines till congestion happens. Or some other entry and exit layout. But I think it should work best to split the incoming track in half, each branch servicing half the stops. Splitting of stops one by one feels like it will block more.

Maybe even add some circuit logic to make the trains enter and leave in a controlled order?

[Aeternus]

You can do it unidirectional too.
A little rough, but you get the meaning below I hope:

Code: Select all

-<--------------------------------<-
->--\---------------------/------->-
     \-------------------/
	       TTT TTT
     /-------------------\
-<--/---------------------\-------<-
->-------------------------------->-

T= Transfer station.
If you need more, put them in series instead of parallel.

[mrvn]

I think I get what you mean but the exit of one bay would still cross the entry of the next bay. When a train leaves from the first station the train for the last station has to break and wait for it to clear before it can accelerate again.

I imagine for a theoretically maxed out design that each train enters the yard at full speed and breaks only to exactly stop at the station. Then it accelerates non stop out of the station and leaves the yard at full speed. Trains would arrive at an interval equal to the breaking distance.

Obviously such a system would be horrible fragile and a one tick mishap could cause a cascade of breaking trains.

[mrvn]

Ok, step one. Here is my attempt to put the maximum number of trains per second on a track. I've managed to send one train every 76 ticks. AT 75 ticks they slowly back up. Surprisingly the trains are not going at their maximum speed. You can see them speed up a bit before entering the yard. Making the exits circuit controlled and timed precisely was key to making it work.

So I wonder: Do I need a longer exit path so the trains can speed up more? Space the signals on the main track differently? Or is acceleration and breaking such that trains/s simply has a maximum below the top speed of trains?

Anyway, next is step two: Bring in a full ore train and empty ore train every 152 ticks each and cross load the ore. My feeling is that N==M is the way to go. As in one waiting bay before every station like in my speed test setup. Any path crossing between waiting bays and station would probably slow things down. Or maybe 2N : M with deeper waiting bays.