Factorio Forums

AndrewIRL wrote:I was wondering how throughput would be affected with 1-4-1 trains. In theory the lower speed of 1-way vs 2-way trains should mean a significant decrease in throughput.

Code: Select all

LL-CCCC,  ratio = 2, top speed = 259.2
L-CCCC-L, ratio = 6, top speed = 134.6

The 1-4-1 train has only 52.93% the speed of the 2-4-0 so I would predict that the maximum throughput will be somewhere in the range: 20-26 down from 64 for the highest throughput intersection.

Maybe you would be willing to test just one intersection, the big 64 throughput cross?

aaargha wrote:I don't know which version those numbers are from but in 0.15.10 both setups have a top speed of 298.1 km/h when rocket fuelled, the 1-4-1 just takes longer to get there.

aaargha wrote:I might be willing to run some tests once the theory seems at least plausible

Mehve wrote:I used this particular roundabout implementation for quite some time without a single hiccup. I'm curious how it stacks up in the tester...

Distelzombie wrote:Ok. How do you see that without testing??

Shokubai wrote:Another common error I see is one of too few signals on longer stretches of track in a junction. Note that the right hand turns only have a chain signal at the end of the path. This means a train must PASS this signal before the strait path will open. By placing a signal at the start of the right hand turn the train only needs to clear the turn to open the path again. Again, Ideally, right hand turns should be long enough to hold an entire train between signals but this isn't strictly required just a nice feature. Also in this picture note the unsignalable triangles.

Distelzombie wrote:Makes sense. It doesnt save even a second, but OCD. XD The "WIDE B" setup seems to be ok though.
Do you have a good junction that you use often?

Distelzombie wrote:

Shokubai wrote:Note that the right hand turns only have a chain signal at the end of the path. This means a train must PASS this signal before the strait path will open. By placing a signal at the start of the right hand turn the train only needs to clear the turn to open the path again.

Makes sense. It doesnt save even a second, but OCD.

AndrewIRL wrote:It isn't about OCD, it is about throughput. Every delay in the intersection affects multiple lines and you get a traffic wave effect if the intersection is nearing capacity. If you only have one train every few minutes then it won't save even a second.

Aeternus wrote:Avoid 4 way crosses in favor of T junctions with at least 4 or so train lengths between any intersections that involve the parallel tracks simultaneously - much better throughput that way.

Shokubai wrote:Lots of signalling advice

Shokubai wrote:I've even played with the idea of a Double T junction in lieu of a cross and it isn't bad.

Aeternus wrote:but I agree with sentiments posted earlier: Avoid 4 way crosses in favor of T junctions with at least 4 or so train lengths between any intersections that involve the parallel tracks simultaneously - much better throughput that way.

Distelzombie wrote:Now I remember hearing that somewhere. You're right. But it doesnt really matter unless you have a megabase.

Shokubai wrote:One other trick I like it to place my normal signals closer together at the exits of stations and junctions. It simply helps each successive train start accelerating a little bit sooner.

aaargha wrote: Note that this may cause trains to stop while still in the junction unless you've got full control of where trains may stop due to getting backed up.

aaargha wrote: Do any of you have a source on this with some actual data on this? It's starting to feel like this is some kind of urban legend, I see it here and there but so far no one has had anything to back it up with. I'd be most interested to see if it actually has some merit.

aaargha wrote:Do any of you have a source on this with some actual data on this? It's starting to feel like this is some kind of urban legend, I see it here and there but so far no one has had anything to back it up with. I'd be most interested to see if it actually has some merit.

Shokubai wrote:I understand what you are saying. This works best in true exits that don't immediately intersect some other cross. The idea is simply that an accelerating train clears each evenly spaced signal at a different rate. Simply adding a half-stop signal between your first two exit signals gives you another check to allow the next train to begin accelerating.

Shokubai wrote:No, purely anecdotal or personal experience and I've done some games with hundreds of trains. I am interested in the math but it either works or doesn't in my particular setup and outside of the odd trick or tip to improve responsiveness any good junction can work if it has space to be signaled properly.

Shokubai wrote:To add to your testing. Here is one I am a fan of in principle but have only used in limited quantity due to my aversion of 4-way crosses. If you do test it, you may play with adding a second signal to the longer stretches of internal track. Also I'm sure i missed a signal in there somewhere scratching this together. I think this is a bigger version of the R-Twister you tested and with more signaling.
2.png
What I found I liked most about this is that on left hand turns you can make the track longer before intersecting the right turn. This makes the junction bigger but means you could add stopping for left turns to clear your strait paths. The junction becomes bigger but also more fluid.

Distelzombie wrote:Well, Xterminator and his guys (Youtube/Twitch guys) have made a map with >350 trains (2-4-2, 1k science packs per minute) They said this several times, even in a tutorial they said this. They are pretty much professionals, thats why i trusted them. XD
Well if you are testing this you can settle this once and for all. Try different train lenghts and 4 lane systems. What lenght are you using anyway?

aaargha wrote:Ah, that would explain why it's such a common notion. I'll have to look around and see if they have some results to share.

Info about the test setup is in the OP. I don't have multi-lane support yet but I'm working on a setup for testing up to 8 lane intersections, it's a bit tricky to get it flexible enough though.

Distelzombie wrote:Rail signals give a track priority over a chain signalled track, I heard. This could cause issues.
Hm. aaargha, could you test if this does increase troughput?

Distelzombie wrote:Rail signals give a track priority over a chain signalled track, I heard. This could cause issues.
Hm. aaargha, could you test if this does increase troughput?

iceman_1212 wrote:I have noticed that many folks overuse chain signals. For a "cleanly" signaled 3-way intersection, I would refer folks to aaargha's 2x 3-way intersection in the first post of this thread.

In this intersection, for example, the circled signals can be replaced with rail signals:

• 1 Remove redundant chain signals: along a single stretch piece of track any chain signal after the first one encountered by a train can be removed*.
• 2 Optimize chain signal placement within the intersection: push chain signals as far back along the track they're on as possible so that trains clear the previous block as soon as possible.
• 3 Optimize output signals: push the rail signals as far back along the tracks as possible, stop when you hit a track you couldn't reach with a train (crossing/merge), go each way on a split, and remove any chain signals you pass. Signals marked with orange are the ones to size the output block after.
• If you value trains being able to change paths while waiting highly stop here. I don't as they almost never have the time to anyway.
• 4 Remove/replace entrance chain signals (only do this if there are other chain signals before any rail crossings!): any chain signal before the one by the by the crossing can be removed/replaced with rail signals.
• 5 Optimize new entrance chain signals: push them forward as close to the crossings/merges as possible.
• 6 Optimize paths that go directly from input to output blocks: these paths should only have a rail signal on them now, add as may as you like as long as you don't start to cut into the output for paths with chain signals, limit is marked in purple.