More trains vs. longer trains

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roothorick
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More trains vs. longer trains

Post by roothorick »

There's a lot of angles on this that I don't have a good idea of how to test.

I played around in sandbox a bit adding empty cars to a train, and found that the speed penalty is surprisingly small. Assuming how full a car is doesn't influence the speed of the train, longer trains is unquestionably the clear winner in terms of theoretical throughput.

Operative word being theoretical.

Biggest problem with long trains is station design. If you use ten inserter pairs to unload each car (five on each side), just two cars will come frighteningly close to the theoretical maximum of the mighty express belt. So you'll need, at a minimum, a separate belt for every two cars. Depending on available space, this could get unwieldly fast.

Or would it? The train isn't at the station all the time. The train will spend more time in transit than at any station. It's already a common tactic to have a chest buffer between the train and your belt; why wouldn't you flood all the buffers at once while the train is in, then empty them in sequence while it's off filling up, so your furnaces are never idle? (And vice versa at your mine, of course).

There's fuel cost too. Is a locomotive's fuel consumption over time or over distance (or a combination of the two)? The former would strongly favor more trains, while the latter would even more strongly favor longer trains.

Longer trains have the added bonus of being safer. Trains in this game have the reputation they do because very short trains are popular. Very short trains are very, very fast, and when passing by, tend to be on the screen for only a few hundred milliseconds. In contrast, just try to be caught sleeping by an 8-car train. You'd have to be drunk.

The takeaway seems to me that you should have as few trains as is practical, and just keep slapping more cars on the end and modifying your stations to suit when you need more throughput. Thoughts?

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Re: More trains vs. longer trains

Post by Mangledpork »

The coal usage is over time. It uses coal to push itself up to top speed and once there, a smaller amount to maintain the speed (i'm pretty sure of that anyway). When slowing down none is used.

Anyway, a problem with longer trains is what happens when you have a bunch of them at a junction (for example a circle with 4 entrances and 4 exits). If a lot of small trains arrive at the same time, it doesn't take long for them to move on and clear the area. With long trains, their length and slower acceleration means it takes a lot longer to get out of the way, and could cause problems in areas where a lot of trains come through. Of course, if you're using long trains you probably won't have that many of them, so maybe it wouldn't be that much of a problem, but it's something to consider. Perhaps the addition of extra locomotives could help that, but then why not have them pull separate trains in that case?
Also, if you have long trains along the lines of 8 wagons, you'll have to build your rails to fit. If the train is long enough to fill 2 blocks when stopped it could cause all sorts of jams. You may not be able to use the conventional loop I mentioned before because it might be too small for such a large train. And your stations would have to be super long to fit them, and even more so if you have multiple trains going to one station. Things get pretty huge pretty fast with large trains.

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darkminaz
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Re: More trains vs. longer trains

Post by darkminaz »

the problem is with a lot of trainstops. i currently got both on my tracks
track a) got a huge train that goes far to fill up
track b) got 5 little trains that keep making stops on their way


long train downsides
- you need more inserters/ boxes to unload
- need longer loops
- take a long time to reach max speed

short train downsides
- you need more, end up using a bit more fuel
- usually add more then 1 so you need signals :P lots of them

i currently got way more coal than i could ever use, so i currently go with the short trains and more trainstations.

i think long trains are good for distance, short ones for near and often pickups.

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micomico
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Re: More trains vs. longer trains

Post by micomico »

I'm changing my train system to use big trains to bring ores from remote outposts to a central station near my base and then smaller trains to bring the stuff from there to processing in the base.

This is the way I found to upgrade the capacity of my rail system, without changing the existing stations that are tightly fit in my factory, that can only support 2 car trains.

More trains with a large network with multiple paths leads to, in my experience, frequent jams and trains wondering about in places they shouldn't be.

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Re: More trains vs. longer trains

Post by roothorick »

micomico wrote:I'm changing my train system to use big trains to bring ores from remote outposts to a central station near my base and then smaller trains to bring the stuff from there to processing in the base.

This is the way I found to upgrade the capacity of my rail system, without changing the existing stations that are tightly fit in my factory, that can only support 2 car trains.

More trains with a large network with multiple paths leads to, in my experience, frequent jams and trains wondering about in places they shouldn't be.
I didn't even think about that. The overly greedy pathfinding is definitely a big downside to more trains.

Here's the strategy I'm going to use:

* One resource per train. Easy enough.
* If multiple mines of the same resource are closer to each other than they are the base, I'll put a transfer facility in the middle of them. Smaller trains will bring ore from the mines to the transfer station, to be loaded onto a larger train to bring the load home.
* If the mines are closer to home than each other, just have one train per mine, each one coming directly home.

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Re: More trains vs. longer trains

Post by Mangledpork »

roothorick wrote:* If multiple mines of the same resource are closer to each other than they are the base, I'll put a transfer facility in the middle of them. Smaller trains will bring ore from the mines to the transfer station, to be loaded onto a larger train to bring the load home.
I never thought of that! I'm gonna use that in future.

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Re: More trains vs. longer trains

Post by ketil »

It is possible to run long train with multiple locomotives to speed them up. If we say < and > are locomotives indicating direction and = is wagon I tend to do something like this <===< for trains not supposed to reverse and something like this: <>==<> for trains that I want to reverse. These can be combined into longer trains so maybe something like this <===<===<===< for a longer one(but never built it myself). I don't like to have even 3 wagons in a train with only 1 locomotive.

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Re: More trains vs. longer trains

Post by HackerKiller90 »

Fuel is never a concern for me as I go coal-less for everything that I can. Toss in some solid fuel and those trains will run for freakin forever. A clever trick is a smart inserter assembly that takes 100 solid fuel from the cargo wagon and via assembly line back to the train for a reload. That is if one is very concerned about refueling just carry some with in a wagon via reserved slot. Fun times

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ssilk
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Re: More trains vs. longer trains

Post by ssilk »

Some thoughts:

Number of wagons:
- it makes no sense to have trains with only one wagon
- more than three wagons begin to visibly slow down the train,
- 4 wagons is still a good compromise, 5 needs in my opinion a second loco

Inserters/Stations:
- the researched inserter stack size bonus is a must! Without it, a number of parallel belts are more efficient :)
- you can place between 6 and 7 inserters per wagon, see https://forums.factorio.com/wiki/inde ... /Positions
- that enables to unload/load a ore-train under 15 seconds.


From the Station-Chests onto a belt (or vice versa):
If I calculate a bit around: it is easily possible to reach a throughput of 3000 items per wagon, if you unload 2 trains per minute. That is no problem!
Inserter-bottleneck: An inserter can un/load only up to ~150 items/minute. So for the best case, that we have 14 chests for a wagon (left + right side) = 14 inserters per wagon, we get up to 2100 items/minute or 1800 in the worst.
Bottleneck of the belts: An express belt can transport only around 1800 items/sec in the best case! So in the best case you can unload around 1 wagon per minute (or 40-50 secs) with one express belt.
So the combination of inserters/belts for unloading the chests always sucks! Always. I found no way to effectively unload chests with using belts, cause their capacity is just much too low. Why is this a problem? Your incoming trains will fill the unload-chests in some time. And then nothing is transported anymore - or the throughput goes into cellar.

Solution: I use normally a separate logistic network for un/loading the chest to/from the trains, cause when you mix the networks, the bots need to fly too long, but with a separated network the average distances between source and target chests get very small and logistic bots can provide their full advantages. I never found a bottleneck with this combination. The number of bots can be astonishing low, far under 200 can un/load 10000 items per minute.
Big advantage: With a separated logistic network, this train station can work also as a very cheap storage for the incoming stuff.

Mixed transport of ores:
- if you have enough capacity, it is no problem to run mixed trains, when you use logistic bots at the target station to sort the things out into the right belts.



See also the wiki and the forum-search for more examples about this.
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Re: More trains vs. longer trains

Post by UpGoing Kerbal »

Thoughts by system;

If you use single track with passing loops then Longer is better than more, as single track will get clogged up quickly as trains have to wait in passing loops and the start-stop of waiting will increase fuel costs.
On double track it's less of an issue, but with more trains having to wait at interchanges increases.

short trains need shorter platforms you need more of them so you might end up with queues forming.

Also since pathfinding is silly avoid multiple routes and single we only have block signals avoid complex junctions.

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Re: More trains vs. longer trains

Post by Ca_Putt »

I've tried multiple Trainstations for one unloading Plattform each with 2 wagonlengths in between. It prevents conveyor Overflow, as you're effectively ony unloading 2 wagons at a time and only requires minimal space next to the track. However one may want to add a second row of buffer chests and it does require a rather Long strait bit of rail around your mainstation.

Sadly, my Map does not allow for such Organisation and I had to move to multiple 2 wagon Trains, also my Mining outposts seldom have enough Output to actually fill more than 2 wagons.

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Re: More trains vs. longer trains

Post by keyboardhack »

This is how i see it:

Long trains can be just as fast as short trains by adding a few more locomotives so the speed isn't a factor. Not everyone uses loops, so that isn't a factor. The fuel trains uses shouldn't be a problem for most people and a good train system should never be able to make trains stuck.

Long Train Positives
They can hold a lot more resources
You only need a few to cover a mine far away from your base

Long Train Negatives
They use up a lot more space
It Takes longer to prepare the mines for them

Short Train Positives
Quick to setup
They don't use that much space

Short Train Negatives
They don't hold that much
You need a lot of them to keep a mine far away busy


Afaik there really isn't a "best" train setup. The trains length should depend on how far the train has to travel from point A to point B.
Last edited by keyboardhack on Sun Aug 31, 2014 1:28 pm, edited 1 time in total.
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Re: More trains vs. longer trains

Post by OBAMA MCLAMA »

I like to use 2 wagons, but when you get late late game, 3 will help.

but i find mostly with 2 wagons, depending on your assembly line. 2 wagons per 25soish elec furnace will leave extra ore in the wagon on 30s interval.
But a lot of everything is a lot of different.
You have length of tracks, the wagon count, the rate at which you take out or put in the ore. rate of how fast you are burning the ore.

The best thing to say is... Plan ahead of time, and build more. Its better to overdo it, that way your factory is not slowing down.
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Re: More trains vs. longer trains

Post by Zourin »

Generally speaking, you should only need enough wagons to match the expected throughput.

You will want one train wagon that carries train fuel, repair kits, and walls for local maintenance.
One train wagon per major mining outpost, and one for every two minor stops. Different mined materials should go in its own wagon, unless you have, say, a small stone and coal outpost

Production outposts (say a chip plant) should have one wagon specifically for imported goods, and one wagon for exported goods (take advantage of filters). Oil resourcing is much the same way, although if you don't have a large and fresh oil field that you're pumping, you can get away with sharing a wagon for full and empty barrels.


Long trains are a solution for more throughput on shuttle systems (single, bi-directional track), and 'more trains' is reasonable for a loop train system where goods may be passed between certain stations without having to stop at others.

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Re: More trains vs. longer trains

Post by SilverWarior »

Using of long trains doesen't necessarily mean having huge train stations unles you are absolutely concerned about express loading/unloading of trains.

You can load/unload train of any lenght with almost same train station setup that you use for smaller trains. How?
All you have to do is add some aditional train stop after your default train stop. You place these so that when train moves to them it only moves for a length of few vagons. How many depends on how many can you unload at once using your current train station setup.

Biggest advantage of such system is that you can actually unload a mile long train while your basic train station setup is optimized for smaller trains.
The biggest drawback of course are bigger load/unload times.
So this setup is not intended if you are conerned with speed a lot.

I used such appraoch in one of my older gameplays (don't hav the savegame any more) where I had train with 8 locomotives and 40 vagons hauling raw resources over great distance from one of my gathering stations to my main base.

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Re: More trains vs. longer trains

Post by ssilk »

I used that also some times and would recommend it only, if there is no other way or if you have more than enough free space left. Cause if you have enough time to un/load, it is easier to make more trains, then that.
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Re: More trains vs. longer trains

Post by MisterSpock »

I suggest 2 Locomotives with 8 Waggons (ore) + 1 Waggon Supply. Its fast enough and hold enough. And if u have large mining sides and a lot of traffic, it will reduce it a bit.

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