Working Diverging Diamond Interchange

[Moratamor]

I came across this design via Google while I was searching and just had to try putting it in CiM2. It's not as neat as I'd like (oh for a snap to grid tool) and the lanes don't split off/merge properly (3 -> 2+1 etc), but it works and the CiMs use it perfectly. It looks to have very good traffic flow, which is what this design is aimed at. See here: http://en.wikipedia.org/wiki/Diverging_diamond_interchange

By using regular one way street for the diamond I was able to get the two sets of lights properly too. It's quite something to watch in motion.

Click the image for larger version - it's easier to see the road markings.


how to take screenshots

 

[douglasrac]

This is absolutely awesome! I made the suggestion for this to be in CiM 2 long time ago. I forgot about that interchange. This was the video I linked: https://www.youtube.com/watch?v=HD-0QnUlLOQ

So happy this works in CiM. It will definitely be in my custom map.

 

[cschweitzer]

This is pretty impressive. I've been fascinated by the Diverging Diamond for awhile now, and had something similar to the DCMI that is on the linked wikipedia page in the works for about a week. The result wasn't too pretty, but it was good experience:



After seeing your more scaled down approach, I tried something less... dramatic. Still not great (I echo your desire for a snap to gride), but I like the result a lot more:



I've only implemented a DDI/DCMI in a single bloated custom map thus far, but even with traffic scale up to 100%, I *never* see traffic issues at the interchange.

Great work!

 

[Moratamor]

That DCMI is what I thought I'd have to build as I wasn't sure I'd get the diamond to work at-grade. Using the one-way street instead of the Expressway is the key.

It has one potential weakness I can't do anything about. With no flow controls there's no way to prevent a CIM entering the diamond, turning left at the lights and immediately exiting. I haven't seen this in my test map, but if you had an attractive off-ramp in that direction it's possible they may path a u-turn through the diamond to get to it.

I'm looking at this bad boy next:

[video=youtube;XDDmE4qoCns]https://www.youtube.com/watch?v=XDDmE4qoCns[/video]

 

[cschweitzer]

That's tremendously beautiful. The six-way diagram on the pinavia site is amazing to contemplate.

I briefly fired up the map editor and tried to create this, but I couldn't manage to force the splines into a pretty enough circle.

 

[Co_Karoliina]

Great work! I really like to watch the flow of traffic in the game and add roads to make the cars flow better. And I totally would love to just see how the traffic flows in this interchange!

 

[Jokurr]

That interchange looks beautiful but I’m curious as to how well the traffic AI is able to handle it? In my experience interchanges with lots of traffic lights that would realistically be synced to allow better flow, clog up in this game.

 

[Smaen]

The problem with the traffic in Cim (2), is the CiM's don't know how to use the lanes properly.

If two motorway roads merge, lets say 3+2 into a five lane road, the cars that comes on the two lane road, should stay on the two right lanes on the five lane road, while the cars coming from the three lane road, should use the three left lanes of the five lane road.

Problem is, the CiMs doesn't do this!
Is it possible to fix this problem? My city got a huge traffic jam 'cus of this!
-
I would love to give that Pinavia intersection a try, but due to the problem mentioned above, I guess it would be a big failure

 

[Moratamor]

That interchange looks beautiful but I’m curious as to how well the traffic AI is able to handle it? In my experience interchanges with lots of traffic lights that would realistically be synced to allow better flow, clog up in this game.

I haven't seen that so far, but to be fair I've not ramped up the population in the test map yet. If the flow became very heavy and one-sided that may be a problem, but you'll still have better flow than you will from a non-diverging interchange in the same space.

 

[Moratamor]

The problem with the traffic in Cim (2), is the CiM's don't know how to use the lanes properly.

If two motorway roads merge, lets say 3+2 into a five lane road, the cars that comes on the two lane road, should stay on the two right lanes on the five lane road, while the cars coming from the three lane road, should use the three left lanes of the five lane road.

Problem is, the CiMs doesn't do this!

That's probably not a CIM failure, it's more likely to be that your CIMs are joining from the two-laner to get to somewhere they can only reach from the three-laner so they switch over. You may need to re-think the design so that they have a clearer path to where they want to go. Can you post some screenshots?

 

[douglasrac]

This is another interesting solution for busy intersections that I wanted to try in CiM: https://www.youtube.com/watch?v=-vzDDMzq7d0. Not sure if its fully applicable.

 

[juju94]

Some History

I came across this design via Google while I was searching and just had to try putting it in CiM2. It's not as neat as I'd like (oh for a snap to grid tool) and the lanes don't split off/merge properly (3 -> 2+1 etc), but it works and the CiMs use it perfectly. It looks to have very good traffic flow, which is what this design is aimed at. See here: http://en.wikipedia.org/wiki/Diverging_diamond_interchange
By using regular one way street for the diamond I was able to get the two sets of lights properly too. It's quite something to watch in motion.

The road in the lower left corner seems to be in the wrong direction...

Historical notes about the DDI(I searched aprox. 4 hours for you!):

The first ones were build in France and are here called "échangeur indonésien" (in english: "Indonesian interchange"):
-in Versailles on the highway A13 (the first build french highway [1941]), this is the first DDI in the world in 1970',
-in Seclin on the Highway A1 in 1980',
-And in Nogent-sur-Marne on the highway A4 in 1987.

In 2000 Gilbert Chlewicki, a first semester graduate student at the University of Maryland, College Park was beginning his graduate work for a master's degree in transportation engineering. He chose to work on a "new type" of interchange and prepare a term about it. He wrote a paper entitled "New Interchange and Intersection Designs: The Synchronized Split-Phasing Intersection and the Diverging Diamond Interchange" in 2003, which was an improvement of the original concept. The first DDI in the USA was build in 2009 on the I-44 in Springfield, Missouri. Many others are in use, in project are in construction in the US.

They are supposed to be safer and more efficient than the normal intersections.... I can assure you it's a pain, it's jammed all the time at Seclin and Nogent ones. I hope you have better ones in the US.
​

I can assure you this, I will never use the I'm making city or perhaps to upset and challenge the player.... I let you continue your tests, good luck to have an efficient one.

tipps: -put a 3rd lane in the middle bridge
-do longer exit lanes

 

[Alex_brunius]

What purpose does the traffic lights serve? I thought the idea behind expressways was to eliminate traffic lights and enhance flow of traffic. Here is how it looks when you plane separate to eliminate traffic lights:

Click me for bigger picture

 

[Moratamor]

What purpose does the traffic lights serve? I thought the idea behind expressways was to eliminate traffic lights and enhance flow of traffic.

That's true, but (in the real world) if you need to build the interchange at-grade then this design minimises the number of lights required and the turning contention.

 

[Butelka64]

Great work! I really like to watch the flow of traffic in the game and add roads to make the cars flow better. And I totally would love to just see how the traffic flows in this interchange!

What we would love to see, is the ability to connect a new road of fewer lanes to particular lanes of the previous road. For example: I have a 3-lane expressway, and I want it to split into 2 different expressways - one 2-lane and one single-lane. I connect the single-lane way to the rightmost lane of the 3-lane road, and the 2-lane way to the 2 leftmost lanes. The same with connecting 2-way roads to one way. For example, I have an avenue with 3 lanes in each direction, and I connect a one-way 3-lane road after an intersection straight ahead of the same direction of the avenue. For now it's impossible to make good intersections like Avenue -> 2x one way road + walkway, because the traffic flow will be significantly slowed down.

 

[bullybeef]

Those diamond interchanges are immense! I have also been playing with solutions to interchanges and the dreaded traffic lights. I've tried roundabouts, which I find tricky to create free-hand; square-abouts, which work well but cims aren't to clever with right of way, but the diamond idea works great, and I've used it plenty of times.


Nowhere near as what I've seen posted here today, but mine do a great job of clearing traffic: http://cloud.steampowered.com/ugc/540706343876147112/3578BC8A31823CDEF09ECD1C40C2CC1AE02DBC77/

 

[douglasrac]

How did you do that Moratamor ? I can't seem to be able to connect expressways in the opposite direction.