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Re: 4-way intersections: Throughput and deadlocks [image heavy]

Posted: Fri Jan 25, 2019 12:22 am
by AlexAegis
hansjoachim wrote:
Thu Jan 24, 2019 9:05 pm
AlexAegis wrote:
Thu Jan 24, 2019 5:52 pm
Sadly I don't know how can I improve this further
So I improved it with correct signals.
I also made a better version with extra right turns.

Original: 30 trains/min set 1

Correct signaled: 41 trains/min set 1

With extra right turns: 48 trains/min set 1
btw: those test are with rocket fuel. With Nuclear fuel the numbers would be higher
Thanks! Yes, I'm using nuclear fuel that's why my numbers are higher. :roll: I wanted to let the trains as far in into the intersection as I could without completely deadlocking it, that's why I don't have chain signals everywhere. Guess it was a bad idea. Also, on every left turn before merging back to the "output" track why isn't that signal a chain signal?

Re: 4-way intersections: Throughput and deadlocks [image heavy]

Posted: Fri Jan 25, 2019 6:22 am
by hansjoachim
AlexAegis wrote:
Fri Jan 25, 2019 12:22 am

Thanks! Yes, I'm using nuclear fuel that's why my numbers are higher. :roll: I wanted to let the trains as far in into the intersection as I could without completely deadlocking it, that's why I don't have chain signals everywhere. Guess it was a bad idea. Also, on every left turn before merging back to the "output" track why isn't that signal a chain signal?

Nuclear explains it partly, but not from 30 to 50.
Left turns are often the limiter so if you have more straight turns or right turns your number would be higher. But also if all trains go left your numbers would be higher as every cycle two trains can pass the intersection.
Your test isn't wrong, it's just different.
The new signals might not give an increase in your test


The last signal isn't necessary, you don't need chain signals for merging.

Re: 4-way intersections: Throughput and deadlocks [image heavy]

Posted: Mon Feb 11, 2019 12:34 am
by Dolu1990
I got a 2 way, 415 trains on 5 minutes => 83 trains/minute (3 length trains)

This solution has some good sides :
- Trains can turn back by crossing the middle section three times.
- It can be scaled without too much cooking
- The flow is good, the main slow down come from the middle horizontal vertical 6x6 cross

Deadlock/congestion of the loops is avoided via wire signals.
screenshot.png
intersection
screenshot.png (916.94 KiB) Viewed 205 times

Re: 4-way intersections: Throughput and deadlocks [image heavy]

Posted: Mon Feb 11, 2019 2:18 pm
by hansjoachim
Dolu1990 wrote:
Mon Feb 11, 2019 12:34 am
I got a 2 way, 415 trains on 5 minutes => 83 trains/minute (3 length trains)

This solution has some good sides :
- Trains can turn back by crossing the middle section three times.
- It can be scaled without too much cooking
- The flow is good, the main slow down come from the middle horizontal vertical 6x6 cross

Deadlock/congestion of the loops is avoided via wire signals.
There are many good things about this intersection
Separating left, right and straight
Multiple lanes to increase throughput in the center.
Staying at 2 lanes
The signals are correct just lacking a couple.
The throughput is significant higher than the best unbuffered intersections.
It also looks good

I haven't checked out the circuitry but do you need it? Well probably for u turn

This intersection is really designed for 2 levels, as everything is in one level in factorio the left turns doesn't make sense. They cross many too many paths. You should let left turn drive to the left first and not to the right first.
The U turn here is horrible as it crosses way too many train paths multiple times. You should have a good U turn before this intersection to prevent trains from taking U turns in this intersection.

There are some lacking signals in the cross where left turns trains "reenter". It should be seperated with signales to increase throughput.

To compare this to the other intersections and to get it added to the list someday, you need to make a 6 car design.

Tldr
Add U turns before the intersections
Add some signals to fix the 'cross'
Left turn is this intersection largest problem and should be addressed
Make a 6 car version aswell

Re: 4-way intersections: Throughput and deadlocks [image heavy]

Posted: Fri Feb 15, 2019 4:37 pm
by Dolu1990
This intersection is really designed for 2 levels, as everything is in one level in factorio the left turns doesn't make sense. They cross many too many paths. You should let left turn drive to the left first and not to the right first.
Sorry, i'm confused, i'm not sure to read your words properly.
When you say left turn, is it from a left hand drive or a right hand drive perspective ?
I mean on the picture, which is left hand drive, the left turn is the first thing the train can do, and it cross nearly nothing.

About wire signals, they are required to avoid having all the 24 inner slots busy, which would create a dead lock.

Re: 4-way intersections: Throughput and deadlocks [image heavy]

Posted: Fri Feb 15, 2019 4:53 pm
by Dolu1990
Were you talking about the left turn after the middle cross ?

Re: 4-way intersections: Throughput and deadlocks [image heavy]

Posted: Fri Feb 15, 2019 5:02 pm
by hansjoachim
Oh I am sorry, its right turns for LHD

Re: 4-way intersections: Throughput and deadlocks [image heavy]

Posted: Fri Feb 15, 2019 5:33 pm
by Dolu1990
Ahhh, ok ^^
How would you " You should let left turn drive to the left first and not to the right first" ? (LHD perspective)

Re: 4-way intersections: Throughput and deadlocks [image heavy]

Posted: Fri Feb 15, 2019 10:07 pm
by Dolu1990
Damned i mixed myself with LHD / RHD.
My question was, what exactly do you mean by "You should let left turn drive to the left first and not to the right first" (RHD perspective)
You mean before the middle cross ?