RoRo vs Terminus (was Loop vs 2-headed train network)

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Re: Loop vs 2-headed train network

Post by Dasani »

Boogieman14 wrote:
Dasani wrote: You can't have a single track that handles a dozen trains at once efficiently when they have to backtrack both ways over the same rails.

No sir, loop for me. Always. There's not even a question.
You misunderstood the question ;) The 2-headed train option isn't about having a single track to handle all trains. It's essentially about using Terminus stations vs RoRo (Roll on-Roll off) (see http://wiki.openttd.org/Railway_station#Basic_stations for examples). The inbetween network is, with some minor differences, mostly the same. You'd still have two one-directional tracks.
I didn't misunderstand, maybe I just wasn't clear in what I was trying to say. My mind tends to wander sometimes.

My factory is big. I ship in ore from multiple locations at once to my furnace farm. Current running 200 electric furnaces. The side-tracks off the main-line where these ore trains drop it off are completely full up. I have 4 trains, 4 cargo wagons long each completely loaded with copper sitting in queue all waiting for their turns to drop their loads. So this one side track has 4 of these large trains on it at once and is made (with future expansion in mind) to hold up to 7 of these trains at once. I doubt i'll go up to that capacity but the option is there.

Point is, I can't see how this would work with a two-headed train. I need all those rails to be long and one-way so I can just slink more and more trains on the same track to wait in queue for their turn to drop so I have never ending, never pausing stream of ore coming down into the factory while also keeping the main line with zero obstacles to slow it down.

How could a two-headed train do this efficiently? You'd either have to make new stops for each train so they don't all block each other up or have offshoots on your already offshoot rail line to hold the reserves waiting to unload, so on and so forth. To me, I can't imagine a practical way of making it work that handles the quantities I deal in. I think it could be done for small-scale operations, maybe even for expansions and outposts that would only need a single train visiting it, you could make it work and get away with it. Say you tap a new oil field and only have a single train ferrying that crude back to the base, sure. But for drop-offs there's just no way it would ever work.

So very limited usefulness I think, unless dealing with small scale things.

And again, I think it looks better. :) Never liked the idea or the visual for a two-headed train. I think a factory that is not only efficient, but looks good too, is the best way. :D

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Re: RoRo vs Terminus (was Loop vs 2-headed train network)

Post by ssilk »

That's basically equal to the thought in my post: viewtopic.php?f=5&t=35806&start=20#p222789
So: Agree. :)
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Re: RoRo vs Terminus (was Loop vs 2-headed train network)

Post by Deadly-Bagel »

Come to think of it what Bentham was doing with Factorio Towns worked reasonably well with two-way trains, which was basically that the rails went straight through the towns and had a stop coming off each side of the rails. It means that when a train leaves the station it can go either direction, keep going through the town presumably to somewhere on the other side, or back out the way it came. It looked quite tidy.

However there are many restrictions, he had problems keeping track of trains turning around when he put different contents in the two carriages, and also for this reason he couldn't have any loops in the rail system so was stuck with inefficient pathing. Also the style of station wasn't compatible with waiting bays or even a queue so trains just queued up on the main tracks and at one point blocked an intersection and caused a deadlock. Also because there are no loops allowed the trains have no other way through to the towns on the other side. Don't think it's really going to work for him tbh but he's not updating it much nowadays so maybe he's realised =P
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Re: RoRo vs Terminus (was Loop vs 2-headed train network)

Post by mrvn »

Same here, the question was unclear.

But now with RoRo vs. Terminus I have to clearly say: BOTH.

A terminus is smaller, takes less resources and is easier to build and for e.g. collecting ore the limiting factor is mining ore, not the amount of trains. A single train can easily carry away all the ore you mine. But then at a depot or smelting station trains from multiple ore fields come together and RoRo has a lot speaking for it to streamline the trains.

Or a mixed setup with RoRo waiting station and Terminus:

Code: Select all

|     ___
|    /___\
|   /_____\
|\_/_______\_______
| ___________/
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Re: RoRo vs Terminus (was Loop vs 2-headed train network)

Post by hi_impact »

I use two-headed trains with a one-way rail system. It simplifies stations for me and throughput can be expanded gracefully with bigger stations.

Loops are good too. The speed difference is noticeable but it hasn't really affected me.

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Re: RoRo vs Terminus (was Loop vs 2-headed train network)

Post by Serenity »

Two-headed trains on two-way track. Terminus stations for most things. I don't like the loops in most cases. For example I can fit more into my current oil drop off stations when trains can just back out again the way they came.

That said, a RoRo terminal also works in such a system. When you want the train to leave the same way it already travels because you want to clear the station quickly, then just do so.

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Re: RoRo vs Terminus (was Loop vs 2-headed train network)

Post by MeduSalem »

I use drive-through stations:
OpenTTD Drive-Through
Together with a standardized modular factory grid, somewhat like this sketch:
Grid
A Grid module consists of 9 Roboports (orange squares) placed at max distance from one another.

The train stations can be placed horizontally like in the sketch as well as vertically (I made the sketch before vertical stations became a valid solution). Don't know for sure, but I think with some extra spacing between the grid modules you could probably fit even 4 stations on each side of the module for a total of 16 loading/unloading stations per grid module, which should be more than enough to deal with anything.

If one makes the stations longer then you can even have a small waiting bay before each station, so that the trains don't stock up on the main track if the train stations are full (though I never had that happen to me yet). If I'd have to do a new map I'd probably increase the grid modules to 4x4 or even 5x5 Roboports... and have a waiting area before the train station and a waiting area after the train station. So that if the mainline is blocked a train can still leave the station, making space for a waiting train that wants to enter the station.

Also it's possible to upgrade the main 2-track system to a 4-track system, given one considers the extra space needed in advance.

The intersections don't have any loops, they look like this:
Intersection
I know that without a loop directly after the station or in the intersections and without 2-headed trains that my trains might take a nice detour to turn around (shortest route is at least going around the grid module) and drive back to the station they came from, but since I use quite a lot of these grid modules there are a lot of alternative routes which makes up for the induced efficiency problem. Also I don't have a ridiculous amount of trains in the system in the first place.

Also I keep my trains waiting until they are fully loaded or emptied... Reduces the amount of trains driving around half empty.

That said, smart usage of the various Grid Modules and smart placing of the loading/unloading train stations inside them helps reducing the amount of detours necessary greatly.

Basically my factory is quite similar to the City Block concept, just that I started mine somewhen back in 2014 already, but I never got around to show a finished base with it due to lack of time and because of how I constantly keep on tearing things down and rebuilding them to keep them up-to-date with new updates and other ideas from the forum or which I had myself. It's almost like a big test laboratory to try various concepts already. :D



But back to the RoRo vs Terminus topic:

Somehow I just don't like RoRo because they don't allow for a train to drive through the station if all tracks are occupied, possibly causing traffic jams on the main track if there are no waiting bays. Also if you use them together with 2-headed trains you have to cross the main track, which is also ineffiecient and suffers the same problems as a Terminal station.
But Terminal stations are somehow even more of an ugly concept which nobody does in reality anymore (and actually a lot of effort is undertaken to get rid of these kind of stations) because they are extremely throughput limited due to how incoming trains cross the same tracks as outgoing trains and vice versa, effectively allowing only 1 train to safely enter or leave at any given time, which renders the whole concept of having a lot of parallel tracks inefficient.

No matter what you do, you should avoid for a train to have to completely cross the main track on entering/leaving the station... because that will result in noticable traffic jams on the main track with the effects propagating through the entire train network. I'd rather accept a detour than that.

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Re: RoRo vs Terminus (was Loop vs 2-headed train network)

Post by ssilk »

MeduSalem, this is interesting, cause I also thought about similar construction.

With 0.14 the train-routing becomes better, but I still would avoid intersections into 4 directions, cause they are slow. :)
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Re: RoRo vs Terminus (was Loop vs 2-headed train network)

Post by MeduSalem »

ssilk wrote:MeduSalem, this is interesting, cause I also thought about similar construction.

With 0.14 the train-routing becomes better, but I still would avoid intersections into 4 directions, cause they are slow. :)
Thanks... It took me quite a lot of trial and error to come up with it... mostly because of how stiff and rigid the Roboport covering is... I almost pulled my hair out several times... and yet I still would have fundamental improvements for a new map that I just can't adapt anymore in my current one because I'd have to tear down the entire base (so not going to happen).


And yeah, 4-way intersections may be problematic but the one I'm using is the most efficient 4-way intersection possible in at-grade intersections. Roundabouts are far, far worse than that.


I also tried to work out a module concept with 3-way intersections using a square grid pattern with offset every other row similar to that pattern:
Pattern
There every intersection would be a 3-way one which allow higher throughput... BUT... and now there comes the reason why I abandoned this idea: One direction (in this case north-south) causes the train to take detours as well because it just can't go Manhatten style. In this case it causes immense additional stress on the horizontal tracks because not only does the default horizontal traffic go there, but the vertical traffic too before it can continue to go vertical.

So 3-way intersections are in theory nice but they just don't work too well with a square/rectangular module grid and I have no idea on how to solve that problem even after I agonized about it for several weeks. Maybe hybrid patterns like that and similar could work:
Hybrid
But in my opinion they only alleviate the problem rather than removing it. Also such patterns are so overdesigned already that I can live with the design limitations 4-way intersections have because in the end Factorio is only a game and its not like we have to find an absolute solution to a universal physical or mathematical problem.


I studied architecture and urban planning for several years and Manhatten style is still the most efficient in my opinion if you are bound to have a square/rectangular grid. During my study years I also designed a city concept with a hexagonal pattern with self-sustaining tiles to decrease overall traffic, which only has 3-way intersections as well and which would solve a lot of problems in real life urban planning, but when I tried to apply something similar in Factorio once it never turned out too well because the game is fundamentally built upon square grid tiles, which makes using things going off-grid like diagonals extremely awkward to use... it leaves wasted space everywhere since you can't use triangular space efficient in a square grid (yeah maybe through approximation but that just looks ugly).

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Re: RoRo vs Terminus (was Loop vs 2-headed train network)

Post by Grimakar »

MeduSalem wrote: I studied architecture and urban planning for several years and Manhatten style is still the most efficient in my opinion if you are bound to have a square/rectangular grid. During my study years I also designed a city concept with a hexagonal pattern with self-sustaining tiles to decrease overall traffic, which only has 3-way intersections as well and which would solve a lot of problems in real life urban planning, but when I tried to apply something similar in Factorio once it never turned out too well because the game is fundamentally built upon square grid tiles, which makes using things going off-grid like diagonals extremely awkward to use... it leaves wasted space everywhere since you can't use triangular space efficient in a square grid (yeah maybe through approximation but that just looks ugly).
Oh, then I am sure you know Brasilia. I am really a fan of planned cities, esp that one. I even tried to rebuild the idea of the street network of Brasilia in Cities: Skylines. Actually in Factorio this would be a bus system. :D
I would be pleased, if you posted some screenshots of your designs in Factorio.

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Re: RoRo vs Terminus (was Loop vs 2-headed train network)

Post by Optera »

You cant really compare Factorio with OTTD in terms of RoRo vs Terminus.
Since OTTD does not allow signals on platforms block size = platform length = max train length, which hampers RoRo for long trains a lot. In Factorio we can add a signal every wagon drastically increasing RoRo throughput over Terminus.

I hardly ever need that throughput though, so I tend to use mostly Terminus stations. They are simpler to set up, take less space and material and the path finder doesn't routes trains through them randomly.
RoRo is something I use when I need massive throughput. When you need to build a stacker the vastly superior (un-)loading speed in Factorio comes into play. In Factorio you can unload a full train faster than it takes one to move from stacker to the loading station. So usually you are better off building a 2 or 3 track station than a stacker.
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Re: RoRo vs Terminus (was Loop vs 2-headed train network)

Post by OdinYggd »

I've wondered for a while now how hard it would be to implement a 'reverse to station' instruction.

Like so, if the train's next stop contained a 'reverse to station' instruction, the train would pathfind in reverse to reach that station.

It would then become possible to program the trains to automatically traverse a Wye formation to turn themselves around without needing a full loop.

Such an instruction would also make it possible to use single locomotive trains on short line tracks by just letting it run in reverse at reduced speed- after all on a short line it wouldn't reach full speed anyway.



With all that considered though, on a train with a locomotive for each direction the reverse-running locomotive probably should contribute its share of power to the train. Even before DMU equipped engines were a thing, locomotives in a train that were functional would more or less always contribute power if required rather than being dead weight. Today's DMU equipped engines will help the train out of the station and over the mountain regardless of direction, then idle down and turn off engines that aren't needed to conserve fuel.
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Re: RoRo vs Terminus (was Loop vs 2-headed train network)

Post by ssilk »

MeduSalem wrote:Image
But in my opinion they only alleviate the problem rather than removing it. Also such patterns are so overdesigned already that I can live with the design limitations 4-way intersections have because in the end Factorio is only a game and its not like we have to find an absolute solution to a universal physical or mathematical problem.
Yes, of course.

In my experiences, the rail-problems in Factorio are the crossings. Once a train stands he stops the trains behind him. And so on.
I had much success by defining some "main-tracks": 2 rails each direction, perhaps 3 before and after crossings. Switches allow to change the rail before crossings, if the other rail is blocked by a stopped train. With that the throughput doesn't just double, it is five or even 10 times bigger, just because the fast trains can keep their speed.

You can see this effect eventually: You are sitting in a car, standing on a crossing, traffic lights are red. The second lane besides you is empty. The lights go green and in that moment a car on the other lane comes and before you can even start, it passes you and is 100 meters before you.

What I want to say: I see this last pattern as a really cool idea, if you define such "main-tracks". :)
Optera wrote:They are simpler to set up, take less space and material
Ah, well, I have one point to mention here: With the bigger throughput and not needing to built up such extremely long trains you don't need so big stations. The trains can also drive faster, as they don't need to carry the backwards-lokomotives. So you need even smaller stations. :P

So the advantage is of course on the side of the Terminus, but is not so big as someone might think. :)
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Re: RoRo vs Terminus (was Loop vs 2-headed train network)

Post by Optera »

Efficiency aside, long trains are more fun to watch.
My megabase real goal was not 1rocket/0.5min, but to give purpose to those 2L-6C-2L :lol:

Having realistic huge trains is also why i played way more with NA theme in OTTD than in Alps which would be my home turf.
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Re: RoRo vs Terminus (was Loop vs 2-headed train network)

Post by ChoMar »

Having played a lot of OpenTTD there are too many differences to compare.
Depending on your mods, OpenTTD Trains can go both ways. OpenTTD has a lot complexer networks, with it being a Train Game and all.
That said, the Terminus Station has one advantage in both: Less space. That leads to other advantages, such as being able to place it more freely and closer to where you need it.
RoRo in Factorio has, as many pointed out, the advantage of needing less locos. In Factorio there is another component, fuel. You will have to refuel both locos vs. one loceo, wich makes the refuelling slightly more complex. I havent decided what to go with, originally i wanted to go with RoRo, but it always was "Damn, that takes a lot of space".
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Re: RoRo vs Terminus (was Loop vs 2-headed train network)

Post by Deadly-Bagel »

MeduSalem wrote:But in my opinion they only alleviate the problem rather than removing it. Also such patterns are so overdesigned already that I can live with the design limitations 4-way intersections have because in the end Factorio is only a game and its not like we have to find an absolute solution to a universal physical or mathematical problem.
You said you don't have a lot of trains flying around so probably not applicable to your situation but if you do have a lot of trains in a grid pattern you could sacrifice some pathing efficiency for efficiency of intersections by removing most of the options for trains to cross tracks. Basically trains would be restricted to turning on the outside of each junction (not across it - if your trains run on the right track they can only ever turn right), and you'd end up with a weird hybrid between junctions and loops where the train can use a whole block as a loop but if you have stations accessible from both sides of the track they shouldn't need to make a full loop combined

Heck, you could just apply this to your high traffic intersections that see the most traffic, forcing trains to turn either before or after it but still allowing them to pass straight through.

eg
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Re: RoRo vs Terminus (was Loop vs 2-headed train network)

Post by Dasani »

This thread has actually made me redefine how my rail systems work.

I was sitting around thinking to myself "How to make a 2-headed train work efficiently", so i started thinking and planning and designing and I came up with a new design that I really enjoy. The best part is, it completely solves all of the issues I had before with trains sometimes being dumb and pathfinding down tracks I didn't want them on. This solves... Everything really. Their AI makes it literally impossible for them to pathfind off the mainline now except when they are specifically going to their designated stops, which is beautiful and it has redefined how i'll be using trains from now on.

Because every single track that leads off the mainline is a dead end, trains never try to path down it and it forces them all to stay on that main line. My little bases/expansions are much smaller and cheaper to make rail-wise because I only need about a third of the rails to build working track to an expansion because they use the same little segment both ways, since only one train needs to visit each expansion, sharing that common track for that tiny stint doesn't matter at all because they all share the main line, then have their own private rails reserved just for them when it branches off to expansions. This new design i'm using is like sweet heaven. :D

I built this particular factory just for testing my new train system and I think it works marvelously. I built the station to hold 5 of my iron and copper trains, 7 of my oil trains (which were backed up the whole time because I was at full capacity on oil), and my various oddball trains like one carrying coal, one carrying stone, and my supply train making sure my defenses everywhere were maintained.

I made a video just kind of showing how it works. Most of it is standing around watching the trains (which i enjoy, almost therapy-like), then I eventually show what the little mining expansions look like as well.

This is definitely the blueprint i'll be using from now on until I find something I like better. It's just so much better than having a bunch of loops. I imagine all the rails i've wasted over the years building those loops. XD

https://www.youtube.com/watch?v=4yBvLL8fQ5E

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Re: RoRo vs Terminus (was Loop vs 2-headed train network)

Post by Deadly-Bagel »

Circumstantial I think, tricky to expand and trains are always forced to do a full loop regardless of how close the outpost is to the factory but as there are no intersections, just merges and splits, trains should theoretically be running at full speed for most of the trip (though your little kinks along the eastbound rail at the bottom slow things down considerably).
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Re: RoRo vs Terminus (was Loop vs 2-headed train network)

Post by Dasani »

If you're talking to me, could easily add a few more rails running through the center to reduce the length they have to run, but I find that the distance they travel is never the bottleneck in production. Only thing that ever slows them down is waiting to get completely full from ore patches. Even if the train takes an extra 30 seconds, or even a minute to loop all the way around, it doesn't matter because it drops it's complete load nearly instantly, then zips back to the outpost and waits to be filled and it is there that the bottleneck occurs... waiting to be filled. I could triple the length they have to run and still not lose efficiency really. :P So I just kept one big loop because I like the way it looks. :)

As for expansion, not sure what you mean, it is veeeery easy to expand on. You can make new little offshoots for expansions much quicker and easier, and you can expand the main line obviously to go off in new directions and cover more area. The length of the rails they sit on at the station were designed specifically to fit every active train I had running. If every single train was waiting to drop their load at once, there would be capacity to hold all of them. If I build new expansions that need new trains, all I have to do is lengthen the rails at the station. That isn't really a big deal. Also, I made them all branch off from the same split because I liked the way it looked, if I weren't as worried about looks could also extend each rail individually and just swap a signal for a chain signal where it crosses over and still keep everything running fine. :)

But ya, the travel time is not the bottleneck, so length of rails doesn't matter until that becomes true. It's also fun to watch them shoot around the track. :D

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Re: RoRo vs Terminus (was Loop vs 2-headed train network)

Post by Deadly-Bagel »

Yeah it depends on the circumstance. Using Bob's Mods you get much more powerful mining drills, or if you've got production of circuits or other high-throughput items you're transporting, or say if you've got an off-base ore smelting facility that handles several outposts of ore and ships them to your main factory.

Also I say expandability because what happens when your offshoots become numerous? What's the point you expand the main loop? The more offshoots you have, the harder it is to expand the loop. Unless you just extend the loop so you've got a smaller loop in a big one, meaning your train network is sort of a bunch of rings as you expand. Though then the rings don't have access to each other which isn't a big deal but you're limited to production being organised vertically.

As I said it's circumstantial. For an advanced train player making a modular base this probably isn't the best design for those reasons. Also playing Bob's Mods and the like with ~10 ores, some ores are a fair distance away and building a HUGE loop like that just to get to that one patch of ore isn't feasible, especially with how difficult it is to get power armour.

For a more casual game when you're only starting your rail later in the game yeah I can see this working, which is circumstantial.
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