Factorio Forums

So I've been looking through rail network tutorials, and have a pretty solid grasp on the basics, but every guide and discussion seems to work on the assumption that you have one rail going each direction, requiring two full tracks to any destination. I'm trying to make a fully operational train network that can handle multiple trains, but using only one track; with bypasses for trains going opposite directions. Are there any discussions or guides out there on this topic? Search has been failing me (or I've been failing it; whatever).

if you have the bypasses close enough to prevent deadlocks, you already have 2 tracks everywhere, unless you only allow a single train at a time on the 2 way parts, which would take chain signals everywhere and would be abysmal. just my understanding of it

I will give you a friendly advice. Never run single rail network with multiple trains. They will deadlock. Such network makes no sense from practical standpoint and can only be some achievement-like goal. This network will never be scalable and will gladly stop working whenever you try to modify it even slightly

Actually, it seems that it really doesnt make any sense to build an Rail Network just with only one Track, since you have already written you wanna build a bypass, why not just use a Failsafe 2 Track System...

Rule of thumb for train networks in factorio:
Use block signals only at entrances to blocks safe for trains to wait and chain signals everywhere else.

Adhering to that rule i see no way a single track setup would ever deadlock. Throughput will be terrible though.

Or just build a circular one-way rail. No deadlocks and decent throughput.

Lav wrote:Or just build a circular one-way rail. No deadlocks and decent throughput.

Circular one way rail physically is no different to a normal two rail system with loops on ends
Saying again, single rail system is a major pain in so many ways. It has low throughput, very limited number of trains, near to no scalability and has low resistance to changes

PacifyerGrey wrote:Never run single rail network with multiple trains. They will deadlock.

you say that like its a fact. it is possible to have one way lines with bypasses, and avoid dead locks.

impetus maximus wrote:

PacifyerGrey wrote:Never run single rail network with multiple trains. They will deadlock.

you say that like its a fact. it is possible to have one way lines with bypasses, and avoid dead locks.

I said this as it will most likely be a fact.
As a railway expert (not shy huh) I can tell that building a single rail reliable system is quite an effort. And as I said resulting system will have loads of limitations with unnecessary complexity

Optera wrote:Rule of thumb for train networks in factorio:
Use block signals only at entrances to blocks safe for trains to wait and chain signals everywhere else.

Adhering to that rule i see no way a single track setup would ever deadlock. Throughput will be terrible though.

Thank you for the advice. That's what I'd sort of been working towards as I cleaned up as-they-happen deadlocks, but I wasn't sure if I was missing something.

As for the rest of the thread... yes, I'm well aware it's not optimal; it's a personal challenge.

There's nothing fundamentally wrong with this setup. Yeah, clearly it has way lower throughput, but in my first game (all I was trying to do was launch one rocket) I used a line like this the whole game with plenty of throughput for what I wanted to do and no deadlocks. This is especially true if your total train traffic is split in multiple directions rather than all passing through this one track.

I also use two-way passing lane setups early on as my rail network is starting out so that I can get it up and running faster with fewer rails (especially true during Marathon playthrough where the cost of rails was significant). Then once the throughput starts becoming annoying, I can upgrade to 2 lanes.

Point being - to those who say you should never run this setup... remember that pretty much literally everyone has different goals and strategies for their factory...

Jarin wrote:As for the rest of the thread... yes, I'm well aware it's not optimal; it's a personal challenge.

That's cool. And it's not like you need all that much throughput to launch your first rocket for example.

Design wise I think you'll want to make the bypass lanes one-way. With a chain signal at the exit and a normal signal at the entrance, for a total of 4 signals per bypass. If the bypass is bigger than one train you could add additional normal signals, just make sure the first block is big enough for one train.

This way they'll only leave the station if there is open space in the next bypass area. No point in placing extra chain signals on the long path since the trains needs to reserve the whole track anyway.

If it's a challenge I will gladly help you in a couple days when I get back home. It's kinda difficult to really help from mobile in the hotel with kids hanging around

PacifyerGrey wrote:

impetus maximus wrote:

PacifyerGrey wrote:Never run single rail network with multiple trains. They will deadlock.

you say that like its a fact. it is possible to have one way lines with bypasses, and avoid dead locks.

I said this as it will most likely be a fact.
As a railway expert (not shy huh) I can tell that building a single rail reliable system is quite an effort. And as I said resulting system will have loads of limitations with unnecessary complexity

As a non-expert, I've built a single-rail design with multiple rails.

I run a 2-rail system throughout most of my base. But a large number of low-traffic regions only serve 1 or 2 trains, and I build those areas with 1-track. Especially at the beginning of the game when I don't have many resources. Of course, at the endgame "megabase" level, its easier to just run a 2-rail system everywhere, but its not too difficult to build 1-track systems. Just have an adequate amount of "waiting" bays inside and outside of the single-track region.

I think it's actually the simplest setup to build for multiple trains. Here's why: No crossings. Signals are simple to setup. You only ever put signals on the bypass and stations. A chain signal entering the single lane and normal signal exiting it. Trains will wait at a bypass till they can drive into the next one.

You have a choice to make though. One headed trains or two headed trains?

One headed trains means more complex train stops since you need to turn the train around. You can do that at each stop or at the ends of the line. The later being even slower and I wouldn't recommend it. If you want that better build a loop. So you probably want a T junction so trains can enter the station from any direction and a second T junction so trains can leave the station in every direction.
Two headed trains make stations even simpler. A simple T junction and you are done. But the extra locomotives will be expensive at the start.

Pet peeve time: OP asks HOW to accomplish a certain task, and the forums erupt in a discussion about why it's a bad idea, with nobody trying to answer the actual question. A few people here are at least adding info, so hurray for the factorio forum I guess

Anyway, a single rail system like you describe will be pretty hard to build, and you'd be the first one to construct one at scale and publish it. It's an interesting challenge though! You'll want some extensive use of chain signals, but you can even go further and have train stackers at each end of long stretches. Sending a group of trains one way, and then a group the other would be much preferred to sending them one by one. A little bit of combinator magic can go a long way to squeezing a lot of performance out of one rail. Interesting challenges for sure! No matter what, you'll never reach the level of throughput you can get from a decently signalled two-rail system, but unique setups are much applauded, so go for it! Dont forget to show it off

Have somone a guide for mono rail 2 ways network?

Poli

Optera wrote:Rule of thumb for train networks in factorio:
Use block signals only at entrances to blocks safe for trains to wait and chain signals everywhere else.

Adhering to that rule i see no way a single track setup would ever deadlock. Throughput will be terrible though.

It is simple to deadlock. Example: You have 2 trains in stations. You have 2 trains trying to reach the same 2 stations sitting in the last bypass before those stations. You have trains in every other bypass between those two stations. Minimum for this is 4 trains total.

But it's the basic problem of having more trains trying to reach a station than can fit in that station. Waiting bays will solve this.

mrvn wrote:

Optera wrote:Rule of thumb for train networks in factorio:
Use block signals only at entrances to blocks safe for trains to wait and chain signals everywhere else.

Adhering to that rule i see no way a single track setup would ever deadlock. Throughput will be terrible though.

It is simple to deadlock. Example: You have 2 trains in stations. You have 2 trains trying to reach the same 2 stations sitting in the last bypass before those stations. You have trains in every other bypass between those two stations. Minimum for this is 4 trains total.

But it's the basic problem of having more trains trying to reach a station than can fit in that station. Waiting bays will solve this.

If you only use block signals at the entrance to a safe waiting bay and chain signals everywhere else it can't deadlock unless you have more trains than waiting areas.

I expect that it might even make sense to have lines going out to outposts be single track. If you use large trains (say 8 wagons) the frequency can be fairly low anyway, and have no waiting bays at all between outpost and trunk line.

(I guess the real problem is that laying track is simply so cheap that you might as well just double track everything...)