New 4-way intersection: Diamond Intersection

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Name Lips
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New 4-way intersection: Diamond Intersection

Post by Name Lips » 22 Jun 2016 03:22

I've been a player of TTD and OTTD for years, but this is the first time I've registered on these forums. (actually I haven't played for a while, and just remembered the game exists, but here I am anyway :P)

Anyway, I saw this article and wondered if I could duplicate this kind of intersection in OTTD:

mentalfloss.com/article/81183/diamond-shaped-intersections-prevent-crashes-cutting-out-left-turns

Obviously the crossover intersections would be a bad idea in TTD, so I used bridges.

Here is an image of my attempt:

http://imgur.com/IZuXbIY

And a brief clip of it working:

https://youtu.be/9Zt6ATMsazo

I don't think it's the most efficient 4-way around, but it was fun to build. :)

lcd_47
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Re: New 4-way intersection: Diamond Intersection

Post by lcd_47 » 22 Jun 2016 07:02

Here's the same thing without sharp turns. The main issues with it are that the lines under the central bridges are doing merges before splits, and the insufficient waiting space on the lines joining the diagonals. Both can be fixed, f.i. like this (for TL 3), and the result is actually pretty decent.

However, scaling the design for longer trains would take a lot of space, and upgrading it to more lines is pretty much out of question. There are other designs that are upgradeable, scale better, are much easier to build, and are still good enough for low-to-medium traffic. This makes the above junction nice, but not particularly useful for OpenTTD. :)

Alberth
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Re: New 4-way intersection: Diamond Intersection

Post by Alberth » 22 Jun 2016 10:42

For more inspiration, have a look at how openttdcoop does things: https://wiki.openttdcoop.org/Junctionary

BTW: Is there anything wrong with uploading pictures to this forum?
Being a OpenTTD developer does not mean I know what I am doing.
Also, other OpenTTD developers may have different opinions.

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Ben1338
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Re: New 4-way intersection: Diamond Intersection

Post by Ben1338 » 09 Jul 2019 13:26

Hi, I have developed this style of diamond junction intersection if anyone's interested, it's simple and also split before merge.
openttd_HXJ44GBEMV.png
4-Way bi-directional Diamond
(531.76 KiB) Not downloaded yet
Feel free to personalize it to your taste.

It was actually inspired by a junction I designed myself a couple of years ago
openttd_ZnKRnCq3nK.png
4-way uni-directional Diamond
(496.19 KiB) Not downloaded yet
So glad I was able to grow it into a fully fledged junction.

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planetmaker
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Re: New 4-way intersection: Diamond Intersection

Post by planetmaker » 09 Jul 2019 13:46

It looks nice and symmetric.

However it is speed-limited for longer trains and works nicely for short trains, but will fail for TL > 4 due to the double s-bend on your junction. you can do that by moving out the bridges one tile. If you want signals after the bridges, you'll have to move-out the outer diagonals also one tile. Doing this and removing the s-bend to have only straight diagonal tracks, it would gain a lot of speed for longer trains up to TL 9.

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Ben1338
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Re: New 4-way intersection: Diamond Intersection

Post by Ben1338 » 09 Jul 2019 14:38

It all depends on how you design it, It's a very configurable junction with possible mainline offsets depending on how you make the crossover junctions.

However, it's not symmetric in the slightest, you can try to make it be, but it would only be eligible for rotational symmetry instead of mirrored symmetry due to the inevitable line offsets from the crossover bridges.
openttd_6cTBVxd0E5.png
(928.84 KiB) Not downloaded yet
In-line version to show the difficulties of curves within the junction.

However, this junction is best suited for trains up to 100MPH in this configuration depending on where they come from, Here are the known junction statistics:

Classification: Suitable for either Single Mainline or Dual Isolated Mainline
Sharpest turn: 4
Cost: Approximately $77K to complete one
Construction Difficulty: Easy
Bridges / Tunnels: yes (interchangable)
Deadlock: No
Hills: No
Natural Turns: Yes
Split before merge: Yes
Area: ~23x~24 (Depending on configuration)
Symmetrical: No
U-turn and Loops: No
Signal type: Original

I tend to compare it with junctions like the Cloverleaf due to their direct mainline design and overall duty for a junction of this type.

Edit: It seems while experimenting with a cloverleaf of the same size mine does perform better on throughput, the only issue is that the cloverleaf can be designed a lot more compact (https://wiki.openttd.org/images/7/7e/Cloverleaf.png) whereas the ~23x~24 of mine is the tighest that you'd be able to get it, ie: making it any smaller would remove any benefits it would have compared to other junctions in the same class which leans more toward ultimate throughput for the size of the junction.

Edit: I discovered that due to its asymmetric design, it doesn't exactly scale up uniformly soo the maximum speed you'd get from the junction depends on which direction the train comes from and how you design the junction.
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openttd_9TCNkxh4XB.png
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