# Anyone have a "diverging diamond interchange" in their area? **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [February 25, 2018, 9:20pm UTC](https://boards.straightdope.com/t/anyone-have-a-diverging-diamond-interchange-in-their-area/809570 "2018-02-25T21:20:04Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![teela\_brown](https://avatars.discourse-cdn.com/v4/letter/t/d9b06d/32.png) [@teela\_brown](https://boards.straightdope.com/u/teela_brown)\ **Post date:** [February 25, 2018, 9:20pm UTC](https://boards.straightdope.com/t/anyone-have-a-diverging-diamond-interchange-in-their-area/809570/1 "2018-02-25T21:20:04Z")
There was an article in our local paper about one of these possibly coming to Silicon Valley, at the interchange closest to the new Apple Park campus. I had never heard of such a thing, so I [looked it up](https://en.wikipedia.org/wiki/Diverging_diamond_interchange). It looks awkward, at first glance, but as I looked at it on a [video demonstration](https://www.youtube.com/watch?v=LqE1Z77ccwQ), it makes more and more sense. It reduces the amount of “conflict points” of a big interchange, and seems clear enough to use if you follow the arrows and signals. Does anyone have one of these near them? How’s it working out? ---
**Author:** ![Silophant](https://avatars.discourse-cdn.com/v4/letter/s/a698b9/32.png) [@Silophant](https://boards.straightdope.com/u/Silophant)\ **Post date:** [February 25, 2018, 9:46pm UTC](https://boards.straightdope.com/t/anyone-have-a-diverging-diamond-interchange-in-their-area/809570/2 "2018-02-25T21:46:58Z")
There’s one (that I know of) in the Twin Cities area, at I-494 and 34th Ave in Bloomington. It doesn’t seem to work that well, because the Blue Line light rail runs in the median of 34th Ave, so it has to have its own signal phase where neither direction of car traffic is able to move. I’ve never used it during rush hour, though, so maybe that’s still preferable to the way it was working before the conversion (from a standard diamond). It is easy enough to use, though. Just gotta follow the arrows. ---
**Author:** ![dwyr](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dwyr/32/363_2.png) [@dwyr](https://boards.straightdope.com/u/dwyr)\ **Post date:** [February 25, 2018, 9:51pm UTC](https://boards.straightdope.com/t/anyone-have-a-diverging-diamond-interchange-in-their-area/809570/3 "2018-02-25T21:51:12Z")
We’ve had one here in Lexington for a few years now. It’s an intersection where people get onto a limited access highway and it was a big mess before the double diamond went in - a lot of accidents. Seems to work just fine. I pass through there frequently and it’s not a problem to navigate. Just follow the lines. ---
**Author:** ![Ludovic](https://avatars.discourse-cdn.com/v4/letter/l/7ab992/32.png) [@Ludovic](https://boards.straightdope.com/u/Ludovic)\ **Post date:** [February 25, 2018, 9:55pm UTC](https://boards.straightdope.com/t/anyone-have-a-diverging-diamond-interchange-in-their-area/809570/4 "2018-02-25T21:55:03Z")
I don’t, but I just heard about them before my most recent road trip when I encountered at least 2 in towns I stopped at. If I hadn’t had them in mind I wouldn’t have noticed anything unusual. ---
**Author:** ![GaryM](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/garym/32/241_2.png) [@GaryM](https://boards.straightdope.com/u/GaryM)\ **Post date:** [February 25, 2018, 9:57pm UTC](https://boards.straightdope.com/t/anyone-have-a-diverging-diamond-interchange-in-their-area/809570/5 "2018-02-25T21:57:21Z")
They’ve built some in the St. Louis area and that seem to be working. One I use a lot is at I-70 and Mid River Mall Drive in St. Peters. It’s been there about 18 months or so. GaryM ---
**Author:** ![Lasciel](https://avatars.discourse-cdn.com/v4/letter/l/e79b87/32.png) [@Lasciel](https://boards.straightdope.com/u/Lasciel)\ **Post date:** [February 25, 2018, 10:03pm UTC](https://boards.straightdope.com/t/anyone-have-a-diverging-diamond-interchange-in-their-area/809570/6 "2018-02-25T22:03:19Z")
there’s a good lot around Atlanta on the bridges going over the various interstates. I know they’re safer, and the ones i’ve seen are very clearly marked, but i’m just waiting for some old person or country bumpkin to drive the wrong way on one of the ‘divergements’ because that is not intuitive AT ALL. ---
**Author:** ![kenobi\_65](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kenobi_65/32/13178_2.png) [@kenobi\_65](https://boards.straightdope.com/u/kenobi_65)\ **Post date:** [February 26, 2018, 12:06am UTC](https://boards.straightdope.com/t/anyone-have-a-diverging-diamond-interchange-in-their-area/809570/7 "2018-02-26T00:06:43Z")
One was built in suburban Chicago (at the Route 59 interchange on I-88 in Naperville) a couple of years ago. It’s a very busy interchange, and traffic would back up tremendously at rush hour. When it was described in the press, I had a hard time visualizing how it would work, but now that the construction has been completed, and I’ve gone through it a number of times, I’m really surprised at just how smoothly it works. ---
**Author:** ![asterion](https://avatars.discourse-cdn.com/v4/letter/a/4da419/32.png) [@asterion](https://boards.straightdope.com/u/asterion)\ **Post date:** [February 26, 2018, 12:08am UTC](https://boards.straightdope.com/t/anyone-have-a-diverging-diamond-interchange-in-their-area/809570/8 "2018-02-26T00:08:22Z")
They rebuilt the NM-14/I-25 interchange south of Santa Fe that way. Haven’t been through it since it was completed last year. ---
**Author:** ![capybara](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/capybara/32/202_2.png) [@capybara](https://boards.straightdope.com/u/capybara)\ **Post date:** [February 26, 2018, 12:35am UTC](https://boards.straightdope.com/t/anyone-have-a-diverging-diamond-interchange-in-their-area/809570/9 "2018-02-26T00:35:15Z")
Four or five in Springfield, MO-- very surprising if you’re not expecting them, but the locals get used to it fast and they seem to work great. ---
**Author:** ![Balthisar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/balthisar/32/2825_2.png) [@Balthisar](https://boards.straightdope.com/u/Balthisar)\ **Post date:** [February 26, 2018, 12:38am UTC](https://boards.straightdope.com/t/anyone-have-a-diverging-diamond-interchange-in-their-area/809570/10 "2018-02-26T00:38:06Z")
I use [this one](https://www.google.com/maps/@42.6655101,-83.2412957,16.48z) fairly regularly, and it’s not really a big deal at all. The first time I encountered it was kind of a feeling of wonder, in the sense that this is unique, but there were no doubts or challenges or learning curves involved. The lane goes where the lane goes. My only complaint is the unreasonable drop to 25 mph while crossing the highway. We’ve been getting a lot of modern roundabouts lately, too, and for some reason there are a _lot_ of people that don’t know how to navigate them. For my own safety, preventing others’ confusion with designs such as this is a pretty nice bonus. For my own speed and convenience, I prefer the roundabouts (no stoplights, you see), but this design is entirely brainless, and works. ---
**Author:** ![kenobi\_65](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kenobi_65/32/13178_2.png) [@kenobi\_65](https://boards.straightdope.com/u/kenobi_65)\ **Post date:** [February 26, 2018, 12:47am UTC](https://boards.straightdope.com/t/anyone-have-a-diverging-diamond-interchange-in-their-area/809570/11 "2018-02-26T00:47:25Z")
> [@Balthisar](#): > > We’ve been getting a lot of modern roundabouts lately, too, and for some reason there are a _lot_ of people that don’t know how to navigate them. I think that this is the big issue with roundabouts. Wisconsin (where my family still lives) has gone sort of roundabout-crazy over the past decade, but as they’re still a relatively new phenomenon in the Midwest, and as a lot of drivers haven’t gone through drivers ed with them being a “thing”, experience has shown me that there are a _lot_ of people who simply don’t understand the rules of how to use them. This is especially the case with the concept that traffic that’s already in the roundabout has right-of-way – I see _so_ many people who just drive into the roundabout, forcing the cars already in the roundabout to slow or stop. I’m in a Facebook discussion group for Green Bay residents (and those of us who have moved away), and it’s now become a recurring joke that 50% of all conversations in that group will come back to “roundabouts suck.” 🙂 ---
**Author:** ![Ludovic](https://avatars.discourse-cdn.com/v4/letter/l/7ab992/32.png) [@Ludovic](https://boards.straightdope.com/u/Ludovic)\ **Post date:** [February 26, 2018, 12:55am UTC](https://boards.straightdope.com/t/anyone-have-a-diverging-diamond-interchange-in-their-area/809570/12 "2018-02-26T00:55:39Z")
> [@Balthisar](#): > > The lane goes where the lane goes. That’s why I haven’t been fazed when I’ve seen the couple I’ve seen. It’s no worse than when roads are diverted for construction and in fact is better since there are lights and full-sized lanes. Although I can understand locals being confused if they’ve driven the interchange a certain way for years and all of a sudden they’re not. ---
**Author:** ![TruCelt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/trucelt/32/523_2.png) [@TruCelt](https://boards.straightdope.com/u/TruCelt)\ **Post date:** [February 26, 2018, 1:50am UTC](https://boards.straightdope.com/t/anyone-have-a-diverging-diamond-interchange-in-their-area/809570/13 "2018-02-26T01:50:42Z")
It seems as though a clover leaf would still be more efficient. I don’t see the point of adding the crossover, necessitating the stop lights? It might handle more cars, but that’s because you’ve built two bridges. We’ve got a couple like that in the area,but I suspect they were built that way to make adding eventual Tollbooths more convenient. Maybe my scale of comparison is just off the chart though. I live about a mile from the America’s busiest interchange. It’s a complicated, multi-leveled, stretched-out, inverted, double clover leaf, and would never work if traffic had to stop along the way. It’s [listed here as the fifth busiest in the world.](https://www.youtube.com/watch?v=aVJcPWgCDHQ) ---
**Author:** ![GaryM](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/garym/32/241_2.png) [@GaryM](https://boards.straightdope.com/u/GaryM)\ **Post date:** [February 26, 2018, 2:23am UTC](https://boards.straightdope.com/t/anyone-have-a-diverging-diamond-interchange-in-their-area/809570/14 "2018-02-26T02:23:01Z")
A cloverleaf uses up a lot of land and, at least around here, seem to be reserved for interstate to interstate interchanges. GaryM ---
**Author:** ![Billdo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/billdo/32/315_2.png) [@Billdo](https://boards.straightdope.com/u/Billdo)\ **Post date:** [February 26, 2018, 2:40am UTC](https://boards.straightdope.com/t/anyone-have-a-diverging-diamond-interchange-in-their-area/809570/15 "2018-02-26T02:40:40Z")
Cloverleaf interchanges also have some technical issues that reduce traffic flow, particularly with the inner legs that go “left” (or around approximately 270 degrees). First, they are usually very tight loops, which reduces traffic volume that can flow. Second and perhaps more important, there is the weaving segment where cars getting onto the freeway from the crossing road have to switch lanes to the main travel lanes while those exiting the freeway to the crossing road have to get to the exit lane from the main travel lanes. The weaving area can significantly reduce traffic volume, as well as being the source of conflicts and accidents. ---
**Author:** ![River\_Hippie](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/river_hippie/32/26_2.png) [@River\_Hippie](https://boards.straightdope.com/u/River_Hippie)\ **Post date:** [February 26, 2018, 3:07am UTC](https://boards.straightdope.com/t/anyone-have-a-diverging-diamond-interchange-in-their-area/809570/16 "2018-02-26T03:07:56Z")
I use the one at Dupont road and I-69 near Ft. Wayne IN regularly. It seemed weird at first but makes a lot of sense when you get used to it. Just keep your eye on the overhead lights and signs. ---
**Author:** ![kenobi\_65](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kenobi_65/32/13178_2.png) [@kenobi\_65](https://boards.straightdope.com/u/kenobi_65)\ **Post date:** [February 26, 2018, 6:15am UTC](https://boards.straightdope.com/t/anyone-have-a-diverging-diamond-interchange-in-their-area/809570/17 "2018-02-26T06:15:07Z")
> [@TruCelt](#): > > It seems as though a clover leaf would still be more efficient. I don’t see the point of adding the crossover, necessitating the stop lights? One of the big selling points, for the one that I mentioned above, is that, for the drivers entering onto the tollway (I-88) from the surface road (Route 59), turning left to get onto the highway no longer has you crossing the oncoming lane of traffic; that’s a big part of what it does to smooth out the traffic flow. The stoplights get moved to the far sides of the bridge that goes over the interstate; you no longer have lights _on_ the bridge (controlling those left turns onto the interstate). ---
**Author:** ![Snowboarder\_Bo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/snowboarder_bo/32/229_2.png) [@Snowboarder\_Bo](https://boards.straightdope.com/u/Snowboarder_Bo)\ **Post date:** [February 26, 2018, 7:04am UTC](https://boards.straightdope.com/t/anyone-have-a-diverging-diamond-interchange-in-their-area/809570/18 "2018-02-26T07:04:58Z")
We have one here in the Las Vegas valley in Henderson; they built it in 2014. I hate it. Everyone I know hates it. It’s unnecessarily confusing and only works because if you _don’t_ slow way the fuck down, there’s no way to figure out where the hell you’re supposed to be or supposed to be going. I’ve seen multiple people start driving the wrong way on a section. I once nearly missed a red light because I couldn’t tell it was supposed to apply to my lane. I also hate roundabouts and would see them all torched, flattened and turned into regular fucking intersections. ETA: Here’s how much I hate it: I never use that intersection or exits or patronize the stores and restaurants in that area, not to punish them but just because I hate having to drive thru that intersection. So I guess it works that way as well: reduced traffic because people don’t want to use the intersection. ---
**Author:** ![ftg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ftg/32/2801_2.png) [@ftg](https://boards.straightdope.com/u/ftg)\ **Post date:** [February 26, 2018, 12:57pm UTC](https://boards.straightdope.com/t/anyone-have-a-diverging-diamond-interchange-in-their-area/809570/19 "2018-02-26T12:57:19Z")
I am baffled by the logic of how these are supposed to work better. Reading the Wikipedia article about things like left turners not having to cross oncoming traffic seems idiotic. Because instead you have _everybody_ crossing oncoming traffic! And you can’t have it setup so that the overpass traffic in both directions are going full bore at the same time. (One of the interchanges near me has almost all traffic being just crossing traffic.) And they are scary as can be. Not just people not knowing they have to cross over, but also people just flat out not staying in their lanes and you don’t have any space to get out of their way. I … just … don’t … get … it. ---
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [February 26, 2018, 1:32pm UTC](https://boards.straightdope.com/t/anyone-have-a-diverging-diamond-interchange-in-their-area/809570/20 "2018-02-26T13:32:03Z")
I haven’t encountered one here around DC or elsewhere. I was assuming this was a way to avoid interweaving but I see a normal diamond interchange does that already. [Next page](https://boards.straightdope.com/t/anyone-have-a-diverging-diamond-interchange-in-their-area/809570.md?page=2)