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Diverging Diamond Interchange

Harley

Harley

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I have been slammed here at my day job for the past couple months trying to finish up the final design of a new Diverging Diamond Interchange here in the Kansas City area. I design all the signals, signing, pavement marking, ITS (intellegent traffic systems, basically all the fancy changable message signs, CCTV cameras, and car counting/sensing loops), and fiber optic lines.

diverging.jpg


If you guys haven't seen one yet you probably will sometime in the next few years. The first US DDI opened up this last summer in Springfield, MO and there are a couple others under construction.

These actually shift traffic to the other side of the road to allow for uninterupted left turns. These are extremely efficient at locations without heavy thru movements. They freak people out when the look at them like this but when you are driving through one they feel pretty natural. Interested to see what some of you think of them :lol:

Take a look at some of these videos:

Video

Video
 
can u show us the direction of traffic via lanes...

bottom right looks like its heading into oncoming traffic. (only lane with no cars on it) is that a 1 way, 2 lane road?
 
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wow that looks really good. I am not in design but I do alot of survey processing making 3D maps of freeways and interchanges. I can understand the work you put into that looks great!!
 
JeremyH said:
I prefer the round-a-bout....
Click to expand...

I do a ton of roundabout designs as well, they are some of my favorite. They just don't work in higher capacity scenarios like this (at least not for US drivers).

robbio4422 said:
can u show us the direction of traffic via lanes...

bottom right looks like its heading into oncoming traffic. (only lane with no cars on it) is that a 1 way, 2 lane road?
Click to expand...

This help? You actually switch sides of the road.

640px-Diverging_diamond_redone.svg.png
 
Hurley0706 said:
I do a ton of roundabout designs as well, they are some of my favorite. They just don't work in higher capacity scenarios like this (at least not for US drivers).
Click to expand...
There is one right next to my local crawl spot.....it makes for some entertainment while I am practicing! :ror:

Personally, I love them....no need to stop...hell, I really don't even slow down at them!
 
Interesting work Harley, pretty cool.

We have something here in New Hampshire that has fawked with drivers since day one...I've seen more head on's and near head on's than I care to mention :shock:

It's not difficult to navigate but for some people it seems a bit daunting and as Jeremy said, it makes for some entertaining situations.

There are two sets of lights beneath the I-93 overpass and that's where the fun starts for most drivers. When the lights change each opposing side has the right of way like a typical intersection, however this one is an "open concept" for lack of a technical term. There are 4 lanes total on each side, two of which are turn only to hop on I-93 and two are straight to remain in town.

There are two large islands beneath the overpass as well and clearly marked lanes to aid in flowing the traffic correctly, but for some reason people still feel the need to approach each other straight on!

Oh, and beneath the bridge at the bottom of the pic is a killer crawling spot!

GoogleEarthManchSt.jpg
 
I can see these interchanges working in places where there are no dedicated feeder roads. But if you exit the freeway then need to get back on you're stuck having to go 1 way or the other and making a u-turn.

I do see how this would be a safer intersection...eliminates the last-second jerks making a left turn as the light goes red.


As for roundabouts, They're especially fun in a semi. Houston has a few, and a little podunk town in Louisiana (Youngsville) has 1 with visions of having many more. They're allright I guess, but I'd recommend making them bigger or just don't spend much on landscaping the centers where the trailers will be dragged across. :mrgreen:
 
CreepyCrawl said:
GoogleEarthManchSt.jpg
Click to expand...


That's refered to as a SPUI (pronounced spooey). Those are very common around here. We actually did a pretty interesting one a few years ago with a really cool truss (difference being ours went over top of the interstate).

Here is a shot of it.

http://www.bing.com/maps/explore/#5...2cg&alt=284.961212&z=20&h=355.052407&pid=5874


Click on the little guy and go to streetview on here:

<iframe width="425" height="350" frameborder="0" scrolling="no" marginheight="0" marginwidth="0" src="http://maps.google.com/?ie=UTF8&hq=&hnear=Kansas+City,+Jackson,+Missouri+64108&ll=38.971042,-94.719205&spn=0,359.996578&t=h&z=19&layer=c&cbll=38.971051,-94.719225&panoid=AdvffntkoyBwm97G2M26kA&cbp=12,120.75,,0,1.47&source=embed&output=svembed"></iframe><br /><small><a href="http://maps.google.com/?ie=UTF8&hq=&hnear=Kansas+City,+Jackson,+Missouri+64108&ll=38.971042,-94.719205&spn=0,359.996578&t=h&z=19&layer=c&cbll=38.971051,-94.719225&panoid=AdvffntkoyBwm97G2M26kA&cbp=12,120.75,,0,1.47&source=embed" style="color:#0000FF;text-align:left">View Larger Map</a></small>
 
I suppose the advantage is that it uses less land than a cloverleaf?

Roundabouts aren't too bad in a semi unless the trailer tandems are locked all the way back :x
 
microgoat said:
I suppose the advantage is that it uses less land than a cloverleaf?
Click to expand...

This design is great when your left turn movement is heaviest. Normally you would have to build a new wider bridge to add left turn lanes to accomodate that movement. This design actually allows you to use the existing bridge and since the left turn movement is now free (you don't ever have to stop on the bridge if you are turning left) you have added a ton of capacity.

It is a very specialized application.
 
Hurley0706 said:
I do a ton of roundabout designs as well, they are some of my favorite. They just don't work in higher capacity scenarios like this (at least not for US drivers).
Click to expand...

In Paris I drove through a roundabout that was like 6 lanes deep:shock:...craziness if you're not used to driving in something like that.

And the roundabouts I've seen here are ususally only 1 or 2 lanes and people don't have a clue how to use them.:lmao:
 
Very interesting.

It looks like it would be very efficient. At first I worried about the cars on one side backing up to the point that they block the other direction, but I realized that the first direction would have a stop light and couldn't even enter the intersection.

I wonder what british immigrants will think of them?
 
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