Train Roundabouts

[Deadly-Bagel]

That junction is somewhat poorly designed anyway. It needs to be spread out a bit more so that you can put in signals on the joining westbound and eastbound rails so that two trains going in opposite directions can pass each other.

[aaargha]

That junction is somewhat poorly designed anyway. It needs to be spread out a bit more so that you can put in signals on the joining westbound and eastbound rails so that two trains going in opposite directions can pass each other.

How is this different from the signalling in the deadlock example? It's that two trains going in opposite directions both can use the intersection at the same time that enables the deadlock. Or are you talking about properly spacing intersections (one longest train between each)?

If what you mean is not the already posted signalling or proper spacing please attach a picture or blueprint string of your design so we both know what we have to work with. I'm pretty confused at the moment

[Deadly-Bagel]

Junction

Rail Junction.jpg (522.57 KiB) Viewed 7022 times

The two signals beside the power pole are the important ones, these allow two trains going opposite directions on the straight to pass each other.

Because I use chain signals on the exits there is absolutely no way this can deadlock with conventional trains. Of course if you make trains that stretch from the intersection to the next signal it can deadlock but we've been over that and that is a long distance.

I've just noticed there is a spurious regular signal in the bottom left, this is a remnant of another junction I had going off there and removed.

[aaargha]

Rail Junction.jpg

The two signals beside the power pole are the important ones, these allow two trains going opposite directions on the straight to pass each other.

That looks pretty much equivalent to the 3-way junctions that are used to make up the deadlocking 4-way junction, except for being RHD.

Because I use chain signals on the exits there is absolutely no way this can deadlock with conventional trains. Of course if you make trains that stretch from the intersection to the next signal it can deadlock but we've been over that and that is a long distance.

What kind of deadlocks are the chain signals on the exit supposed to prevent? The only effect they seem to have is to make the intersection longer (minor throughput loss)?

Agreed on the importance of proper spacing. Would you also agree that there is no way to signal the intersection here that would allow simultaneous use of opposing rails while still being deadlock free? If not, please post a picture of how you'd signal it (LHD), I'd love to be proven wrong on this.

[Deadly-Bagel]

The chain signals on the exits prevent trains from stopping there at a regular signal but blocking the intersection due to their length. I found that even a 1-2 train would block the junction if regular signals were used. In theory it shouldn't be a problem but as you say if you put two junctions next to each other or loop it around then having this extra chain signal prevents those deadlocks. The loss of throughput is indeed very minor.

Pretty sure this should do the trick for your left-sided setup, though you'll want to check it over and test it.

LEFT JUNCTION

Left Junction.jpg (606.71 KiB) Viewed 7001 times

Same rules, anything before and after where rails intersect is chain signals, just noticed I forgot a signal at the start of the westbound lane but I can't be bothered redoing it lol

[aaargha]

The chain signals on the exits prevent trains from stopping there at a regular signal but blocking the intersection due to their length. I found that even a 1-2 train would block the junction if regular signals were used. In theory it shouldn't be a problem but as you say if you put two junctions next to each other or loop it around then having this extra chain signal prevents those deadlocks. The loss of throughput is indeed very minor.

Ah, that sounds like an issue with too small exit blocks. I'm not really sure that your approach solves it, but it may help mitigate the problem. (The second half of this album has details.)

Pretty sure this should do the trick for your left-sided setup, though you'll want to check it over and test it.

Left Junction.jpg

Same rules, anything before and after where rails intersect is chain signals, just noticed I forgot a signal at the start of the westbound lane but I can't be bothered redoing it lol

While it's true that it won't deadlock in that way, and allows simultaneous use of opposing rails, it also does not allow 4-way traffic What I meant was that in the linked design is it possible, by only changing signals (rails are fixed), to make it deadlock free while still allowing traffic from/to all directions, and allowing simultaneous use of opposing rails?

I'm thinking it's not (unless we're using 1-1 trains), the 3-way junctions are simply placed too close to each other.

Junction BP-string if you want it

H4sIAAAAAAAA/51Y7W6jMBB8lSi/SYSNgUQRz1IhsFpLqamAnq5CefcDG11KsM0yf1qp3dldz36ydXO4N1V5P7wVg9S96pXsimHQ5acsjl3flur9oz+Nv+7H
6Kvpxv83uhj+Ficmop/xZ/Z4RATpy6tw9d3+kbVTcWpk2SOqVSsr8/eUZGR2SVCs5GsjYsdLBO3Zs0d8D0lE4Vl1vEd1TGGGs0k2/c0Mp3lkjFx+AxNKvJOV
PUGAXVeoZ5JM4qdOvetyZYyfTXpdzh6DBlp9lEq7FVyfeBIpYsVJSuFk9bic8rjcOpeeQ7wEHiec+Jz0UJ5NULE/bbhAgRwFxiDQZjgCRMlhKDkMJYeh5KDc
oNTAaYPhQFpC1rz1b4ZT4m6kAVsgI2AAwHgH88vLiF0KFpRkJGtgtNG6Qwsd7SxoK0N7J9qsg9NhYxdkblRgDiZ2jrHlHGPkOcjmQciXCkgZNzdQDqyvfAWk
7E/5K0WkeW2Mxfth8SuMbQeEsQ06A6G00Pjs2Ue9tEzrYeL2099kEgOipsmcJV7f/HzM+Rn79rTNPYsDY0+AOA7iYgxnOiGCA3lhIC8M5IWBvIC0gKwESPGX
z2vJkZaWE8YjxiJmC8sQjHkszGBSgTkMlkyoQr1JxVdZRdv7MB7BpgX2SLAlgxNgMpZB+5Cdc8lyWpGK24RhYZRwx5jPGIlvewt+Nl3J49tecrLgIcjpHv8P
JH63XN3v2OgCF9KBydQiTXRSSrwXGq1EWaOWdrS0ammyRi3tzGrVjrKPSFWNnu7XNnDF0P98jVjVy89j9IzrcRTUtRyRI+bWyv671Ye3m9T1P4xVWe4PFwAA

[Deadly-Bagel]

Why not? Same design, just doubled. Now I'm more awake I've replaced a few chain signals that can be regular signals. Normally all those leading in to the junction can be regular however there are two that are still an exit from the previous junction so they remain chains.

double left junction

Left Junction.jpg (616.37 KiB) Viewed 6976 times

blueprint

H4sIAAAAAAAA/6WZ3W6rMAyAX6XqNZ2wE0hRxbNMFaANqYOpZUdnqvruh79x1jYhjn3Vi+arky/GMWnZbk5tcTxtXvNr1XR1V1eX/Hptjh9Vvr1052P99t7t
+o/TNvpsL/33bZNf/+Y70C9J9N1/pi/J7RYRiL0NKL7Of6rSGiCZx0M/Pirrc1WM3yWkYMv09O9ow8Bd8X6sm92lfmuOT5Qambt4+p62c/HMEdZl7MvSQQ41
VfriAUO3iQwsIeLQEDEtExCm8cm9MaTNbg62v4cVJQOVNa4OTKfMDrvjZtawCTkPM9ouaKuYhCLGOkFDmaAZQBO6rvSJMqQl4rz5mpM5mEpgLYFRAscCGCTC
QCIMJMJAIgwkwiS+JLpE6SVgBa7AgzrrzexJuSr4SkzFn27CRw0fzbiSfp6fB0spaWd8W7PGChSDwDEIJIPP8gqLAlcocIUCV+hz5T55cUoqe0p5m/d4NeBa
56SHsPgbBkp7sTZbygGCjBqzHCAPMKWTMjZNhqxpv7JcH5s9GVZUVvEs/5QZ53L9dfEBBeqMAfimQGIZBs0x8yFAPqvY6LhaYOWjcQd1PgJTA4WufXWfd7iA
/sIwlhOejvlKIPCNBVcCEl5YgNXWpQJWC1gUsDGfBYErELgCgSsQuAKBK4EqgSmPKOezHdtqAu0sFvjl6wU2qdhkwiYNm8z4hviKgO8IPJKcCYjWDKQ1OXy9
wPeLfL/I94v8JES+pmm+D5ePhLeDgdIr/a719E8fIQhIAucFqeeqY09qaobOMmVdTI+NZUq4ep+Pur3LtbfKGOJfAvNDTh0+/XgW9uPU4XNmAnkTAPm70LMh
RRDC1qDCDE3jb1FdtM3wL+A06/zafX/2fN1VH9vo/9K2/cCmrHq6Zw7nqvs6N5vXQ9WU/wDGql5AVRwAAA==

[aaargha]

After about one minute of heavy traffic

DB1-lock.png (1.45 MiB) Viewed 6960 times

Now I'm more awake I've replaced a few chain signals that can be regular signals. Normally all those leading in to the junction can be regular however there are two that are still an exit from the previous junction so they remain chains.

This seems like a sure way of inviting deadlocks. It's basically the inverse of the golden rule of intersection design from here (it's really good). It's also why we don't need to involve trains changing path to deadlock it.

If you want to try another configuration I'd be happy to test it for you.

[Kelderek]

Why not? Same design, just doubled. Now I'm more awake I've replaced a few chain signals that can be regular signals. Normally all those leading in to the junction can be regular however there are two that are still an exit from the previous junction so they remain chains.

double left junction

The attachment Left Junction.jpg is no longer available

blueprint

H4sIAAAAAAAA/6WZ3W6rMAyAX6XqNZ2wE0hRxbNMFaANqYOpZUdnqvruh79x1jYhjn3Vi+arky/GMWnZbk5tcTxtXvNr1XR1V1eX/Hptjh9Vvr1052P99t7t
+o/TNvpsL/33bZNf/+Y70C9J9N1/pi/J7RYRiL0NKL7Of6rSGiCZx0M/Pirrc1WM3yWkYMv09O9ow8Bd8X6sm92lfmuOT5Qambt4+p62c/HMEdZl7MvSQQ41
VfriAUO3iQwsIeLQEDEtExCm8cm9MaTNbg62v4cVJQOVNa4OTKfMDrvjZtawCTkPM9ouaKuYhCLGOkFDmaAZQBO6rvSJMqQl4rz5mpM5mEpgLYFRAscCGCTC
QCIMJMJAIgwkwiS+JLpE6SVgBa7AgzrrzexJuSr4SkzFn27CRw0fzbiSfp6fB0spaWd8W7PGChSDwDEIJIPP8gqLAlcocIUCV+hz5T55cUoqe0p5m/d4NeBa
56SHsPgbBkp7sTZbygGCjBqzHCAPMKWTMjZNhqxpv7JcH5s9GVZUVvEs/5QZ53L9dfEBBeqMAfimQGIZBs0x8yFAPqvY6LhaYOWjcQd1PgJTA4WufXWfd7iA
/sIwlhOejvlKIPCNBVcCEl5YgNXWpQJWC1gUsDGfBYErELgCgSsQuAKBK4EqgSmPKOezHdtqAu0sFvjl6wU2qdhkwiYNm8z4hviKgO8IPJKcCYjWDKQ1OXy9
wPeLfL/I94v8JES+pmm+D5ePhLeDgdIr/a719E8fIQhIAucFqeeqY09qaobOMmVdTI+NZUq4ep+Pur3LtbfKGOJfAvNDTh0+/XgW9uPU4XNmAnkTAPm70LMh
RRDC1qDCDE3jb1FdtM3wL+A06/zafX/2fN1VH9vo/9K2/cCmrHq6Zw7nqvs6N5vXQ9WU/wDGql5AVRwAAA==

You have rail signals at the start of your intersection and those should be chain signals instead. Rail signals need to be the last thing you see along each possible path and there should always be room for an entire length of your longest train to fit in the space after a rail signal.

How I would do it

Rail signals at the red circle locations, all the rest are chain. Assuming of course there is room for full sized trains after each of those rail signals in the space not visible here.

Left Junction fixed.jpg (615.71 KiB) Viewed 6958 times

[Engimage]

Man this is such a mess from you all. Its like you messed up that this is left-side drive rails? Why do you all put chain signals on exits while putting normal ones on entrances?
Total crap

[aaargha]

Rail signals at the red circle locations, all the rest are chain. Assuming of course there is room for full sized trains after each of those rail signals in the space not visible here.
Left Junction fixed.jpg

Better, but still not safe from the pathfinder. Though it's unlikely that the deadlocks caused will require player intervention to resolve, so that's a plus.

K1-lock.png (727.01 KiB) Viewed 6950 times

Man this is such a mess from you all. Its like you messed up that this is left-side drive rails? Why do you all put chain signals on exits while putting normal ones on entrances?
Total crap

If you want to make a better solution I'd be happy to test it for you, provided that you stop being a dick about it that is.

[Mehve]

If you want to make a better solution I'd be happy to test it for you, provided that you stop being a dick about it that is.

In all fairness, I think he might be referring to Bagel's Double-left junction, which has all the signals are all on the entry points. Were you using a blueprint reversal/flipper mod? Those don't play well with rails.

Edit: Oh, missed the above part about positioning the chains on exits to buffer exiting zones.

[aaargha]

In all fairness, I think he might be referring to Bagel's Double-left junction, which has all the signals are all on the entry points. Were you using a blueprint reversal/flipper mod? Those don't play well with rails.

Edit: Oh, missed the above part about positioning the chains on exits to buffer exiting zones.

That's what I figured, but having a point is no reason to be a dick about it. As for what tools Bagel used I can't say, the original blueprint I've posted is made for LHD, and the description makes me think it's as they intended it to be.

Anyway, I'm mostly just here to deadlock things, so if you want to give signalling the intersection a try I'd be happy to test any design you submit.

[Kelderek]

Rail signals at the red circle locations, all the rest are chain. Assuming of course there is room for full sized trains after each of those rail signals in the space not visible here.
Left Junction fixed.jpg

Better, but still not safe from the pathfinder. Though it's unlikely that the deadlocks caused will require player intervention to resolve, so that's a plus.

K1-lock.png

Man this is such a mess from you all. Its like you messed up that this is left-side drive rails? Why do you all put chain signals on exits while putting normal ones on entrances?
Total crap

If you want to make a better solution I'd be happy to test it for you, provided that you stop being a dick about it that is.

This has me questioning my understanding of how chain signals work. I may send you a PM of the right hand driving intersections I've been using,

[impetus maximus]

golden rule of intersection design from here (it's really good).

where are the other parts? i don't see anything about Factorio on their page.

[Engimage]

Rail signals at the red circle locations, all the rest are chain. Assuming of course there is room for full sized trains after each of those rail signals in the space not visible here.
Left Junction fixed.jpg

Better, but still not safe from the pathfinder. Though it's unlikely that the deadlocks caused will require player intervention to resolve, so that's a plus.

Man this is such a mess from you all. Its like you messed up that this is left-side drive rails? Why do you all put chain signals on exits while putting normal ones on entrances?
Total crap

If you want to make a better solution I'd be happy to test it for you, provided that you stop being a dick about it that is.

Sorry for the "dickness" the post was made too late at night for me and I just did not have time for the right arguments.

Yes I was refering Deadly-Badgel's designs (several last from him). I can understand having chain signals on exits to extend safely zone but you just can't use normals on entrances.

One you have on this screenshot is perfect signaling-wise but is deadlockable by design. However this design is much less deadlockable compared to roundabout in 0.15 as the train can't deadlock itself and repathing will be much less frequent in 0.15.

[aaargha]

This has me questioning my understanding of how chain signals work. I may send you a PM of the right hand driving intersections I've been using,

I wouldn't worry too much about it, most of the time these kind of deadlocks I'm causing are really rare. What I'm using to create the deadlocks is the issue described here (it's a kind of race condition), it's also what causes the roundabout in the OP to deadlock itself. If there is a split after a crossing or a merge the intersection is probably vulnerable to this kind of deadlocks. The underlying problem can, as far as I can tell, not be solved with signals. Signalling can decide if there is a risk for deadlocks or not, and whether those deadlocks will require player intervention to resolve (not 100% sure on this last part, but 98% ).

Please note that even if an intersection is vulnerable there are a lot of things that need to line up for the deadlock to actually occur so most of the time they're really rare. The reason that it's almost only roundabouts that we see posted with this issue is that they only require one train to deadlock, this makes the risk way higher. Whether it becomes a problem depends on the rest of the rail system. Is there another path for the train to switch to? Is the speed of the train such that it will find a red signal while in the intersection (this is what triggers the pathfinder)? Is the other path a better option than the current one? That it will happen to one train is not that unlikely, that it will happen to two at, basically, the same time, pretty unlikely.

However if you want your intersections to be strictly deadlock safe take a look at the one in my first post in this thread.

where are the other parts? i don't see anything about Factorio on their page.

Here it is, it's the one linked on the subreddit sidebar.

[Deadly-Bagel]

This seems like a sure way of inviting deadlocks. It's basically the inverse of the golden rule of intersection design from here (it's really good). It's also why we don't need to involve trains changing path to deadlock it.

If you want to try another configuration I'd be happy to test it for you.

Derp yes major brain fail my bad xD not awake as I thought apparently. Put those chain signals back in.

As for what tools Bagel used I can't say

That would be regular blueprint string, an 18 month child, a wife with a chronic pain disability, and a full time job =P

take 2

Take2.JPG (230.45 KiB) Viewed 6905 times

blueprint

H4sIAAAAAAAA/6WZ326rMAzGX6XqNVTYhD/VxLNMVYs2pA6mlk1nQn33A6HnrJQkOB9Xkzp/dvKLYyfk1GzOzfFw3rwWXVm3VVuV16Lr6sNHWWyv7eVQvb23
Yf/nvA0+m2v//6Yuuj9FSCr4KUKObrdAYJ37GI+uKfdwLTW+u059XD8YH78u3+XJ6DjRtnQLTtWlPOrfE58hqd8og1F4fD9UdXit3urDTMG7MZraJY/x1NSD
Ubt/kHowUBIG2RyB8kHAPiMSGt9d+6Tpo7F9skyD7YQ/y0akg+SPwliSYPEsnvLOmNyWMPa4+1nYRJ5muTTL1IxJImEyG1smGBul4+DSnfe0EqMyE00xjgap
8k8YzlFhigoVKmRUiMIhFA6hcAiFQygcQuGgbFA0cNpgOhCLK5q11ujeFpuLtiMWSARcAHC9nfllJTKeeCZIUlE0cLXRfYdudLSyoKUMrZ1osUa7A9qOnP3P
3nJZjT2Xpz03XU7Q8UxOjoCuE1N8PyhPw5LcwdK4lys+A5cJngklh8vsGVQmnmdu5BSL9dkCpgU945Q15Mi8ukv1K4JgEa2bLOXr9OHdQbSz3FsW9bROz6vk
2Sr1nV1kO7tbd8dwA4rNaWJvjrEWiRdWrZrav2IVed9oeCHw4oWG/XW6gSC6FNQpUMegDuRCIBcCuRDIhUAuBHIBsYBUHFDsu/25QojuBiHGEaOIxcIyBCOP
LTOYVGAOg1vGtUOtScWzrJKdajCOYNECayRYksEOADYcsL8NU0sddwZTGx6/KyrnGdrY+FOTUHaMzZ/HKTgKDfeE/W15XOPn39T5POE4zvB/ufAzxN57+sPs
ZW9Ges/LTAenwqcG7VVoq92yGDvxOu5aL5+D7CFGz0F5uJXZarey17zRrcxWu/VIj8H2FlTHph4eT0e2Rdf+fPbaqi0/tsHvAmx7w/pU9spe83Ip269LvXl9
KevTXyLhm26MHQAA

However this design is much less deadlockable compared to roundabout in 0.15 as the train can't deadlock itself and repathing will be much less frequent in 0.15.

Wasn't sure if they'd fixed this already, if your trains are liable to change direction in the middle of a junction then it doesn't really matter what your signals are, though I question how a train going full speed intending to go forward suddenly stopped to turn a corner. The best way to avoid this is to have as few loops as possible

[aaargha]

This is what I get for taking too long to finish my posts, half of the discussion passes by while typing.

As for what tools Bagel used I can't say

That would be regular blueprint string, an 18 month child, a wife with a chronic pain disability, and a full time job =P
Take2.JPG

Ah, I see you are playing on the hardcore difficulty
Take two, while being much more resilient than take one , still falls prey to the pathfinder. I'd say it's about equivalent to Keldereks solution.

DB2-lock.png (1.03 MiB) Viewed 6899 times

Sorry for the "dickness" the post was made too late at night for me and I just did not have time for the right arguments.

Yes I was refering Deadly-Badgel's designs (several last from him). I can understand having chain signals on exits to extend safely zone but you just can't use normals on entrances.

One you have on this screenshot is perfect signaling-wise but is deadlockable by design. However this design is much less deadlockable compared to roundabout in 0.15 as the train can't deadlock itself and repathing will be much less frequent in 0.15.

No worries, we've all been there some time or other.

Yeah, I read about the changes when building stuff, hopefully that will improve things in the wild, but so far I've not seen anything that breaks my tests.

[impetus maximus]

Here it is, it's the one linked on the subreddit sidebar.

danke