Diverging Diamond Interchange comes to Washington State
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- Опубликовано: 14 сен 2016
- WSDOT will build the state’s first Diverging Diamond Interchange (DDI) at Interstate 5 and State Route 510 in Lacey. DDI’s are a proven way to move more people and reduce the potential for collisions by reducing conflict points. This project is scheduled to begin in the 2018 construction season.
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DDI visualisation proudley presented by Cities:Skylines
Alex graphics on skylines is far better than these IBM PC jr era renditions
When I took a first look at the thumbnail, I really thought that
haha I thought it was Skylines video at first
When you noticed it was not a cities skylines gameplay but an info video... Lol
plus i dont think u can change the direction of traffic on a 2 way road in cities, even with mods like tmp ,next
Anyone else clicked on this because it looked like something you could build in City: Skylines?
but still, I think my solution on City:Skylines works better, elevation and underpasses! no more traffic lights no more traffic jams!
Haha funny you should mention. I once uploaded a DDI to the Workshop. It's labeled as a DCD Interchange (double crossover diamond). Go ahead and give it a try!
lol Its pause in the background.
Joe Smith
Haha, awesome! =D
AdenineMonkey
Yes
Will definitely try this in Cities:Skylines!
There are a few assets you can download as well. I've used this intersection a few times, and it can be useful in minimizing traffic.
Uhm... I actually did it and it worked. It's just not that good at managing traffic. The problem being of course, the intersection points. I eliminated those points and it works like a charm.
This is true. I often spend a fair amount of time with a traffic management mod, making the lights run properly in my cities.
So what mods do you guys recommend me?
Traffic Manager: President's Edition is the best I've found. It has a lot of features, but you only really need to use the ones you need where you need them most.
Best thing they ever did here in Rochester, NY. We had an awful intersection here. we all thought it wasn't going to work, but honestly this is amazing! You'll be amazed how easy it is to navigate. You don't even realize youre diverging. It's the same concept as a subway system when it diverges for other trains, etc.
Absolutely amazing engineering! Much easier than it makes it seem when you watch the videos :)
I wish they would implement these all over the world they would reduce traffic and reduce accidents.
Thank you, WSDOT, for having the courage to try something new and innovative. You'll hear a lot of criticism at first, but it's obvious you've done your homework and will be proven right in the end.
For a regular city it might do its designed purpose. However we are talking about regular city type cities. No visiting on large scale for example Las Vegas is barely doing its first one if you ever visited by driving you would know what I mean. However it’s winter they’re slow season but even then people show up. So if it works they can jump over to that hole city adding additional diamonds they surely need it. I’m saying this because no other city is like Las Vegas……
@@anthonymartinez4307 its crazy to me in 2024 with all the technology we have that anybody would still go to vegas!🤣🤣🤣 its got to be all old ppl and boomers right?!?!?!
I'd seen this type of interchange in the game Cities:Skylines but didn't know there was one near Olympia, where I visit my daughter several times a year. On my way to pick up some takeout food during a recent visit, I happened to drive through the one described in this video and I was absolutely delighted. It wasn't any more difficult to figure out what to do than in an ordinary junction.
The 50% reduction in accidents speaks volumes. And as an avid cyclist logging over 3000 miles a year, I can attest to the reality that the current traditional bridge /traffic design is one of the most hazardous situations I encounter anywhere, which I avoid if at all possible. I really would appreciate going down the middle even if it meant waiting at a light or two. The main risks involve oncoming left turns and also same-direction right turns when I'm going straight but along the right side of the road. It appears that much or all of that risk would be mitigated. Overall, it sounds like a proven improvement and well worth deploying. I hope it is a great success that gets duplicated elsewhere (like roundabouts have been).
I suspect that is a conservative statistic, Especially as folks get more familiar with the intersections, safety will improve even more.
Bike lanes would work better for serious cyclists than being forced to dodge pedestrians on a so-called "shared use path".
What a great explanation! I'm extra glad to see that pedestrians and cyclists have been considered properly with the DDI.
I drive through one of these regularly that was built a year ago here in NC. It's weird when you drive thru it, but there is no doubt that traffic flows better overall.
Same in Lex KY.
would you say its faster traffic flow than a roundabout?
We have numerous DDI along I-15 through Utah County. They upgraded a dozen interchanges a few years back and they are amazing. Traffic through them is fast and efficient as there is very little confusion as to where you go and when you can turn. We have numerous roundabouts as well and they cause constant headaches as people don't know when to yield, when to go, when not to stop, etc. And multi-lane roundabouts are the 7th circle of hell.
mycroft16: Roundabouts surprise first-time encounters. Following the faulty but common principle that the fastest car has the right of way, the traffic inside the roundabout is a sitting duck as the approaching driver suddenly finds the car to his left (or to his right in the UK) is unable to yield. Here in NC we have several new roundabouts where unsuspecting drivers have ploughed straight across because they approached too fast. CRUNCH!!
There's a very small version of the DDI outside Three Rivers, Michigan. the math and theory behind this interchange makes complete sense in a warm climate. Add heavy snowfall and an ice pack on the pavement that lasts for two months (blocking the ability to see lanes) and you have a recipe for disaster and very frustrated drivers in practice. Warm climate? Yes. Snow Belt? Most certainly not.
A clever approach that breaks from traditional traffic concept in that it reverses the orientation of directional lanes briefly along the through route. Kudos to whomever designed this.
Good job explaining this!
Dittos!
There is one of these on 34th ave and 494 in Bloomington MN just outside the small (Humphrey) international airport terminal (and very near the Mall of America). To add complexity, the lightrail runs right through the middle of the ddi. It _was_ confusing as all hell before you get used to it, then you realize, holy shit, this thing actually works. It flows way more traffic than the interchange did before. previously, you would wait 2-3 light cycles, now you go through on the first one every time.
It still sucks. You shouldn't need to wait for any lights. USA should really try to look at how we do it in Europe with roundabouts for highways...
This is speculation but I would guess there are far more cars/capita in the US as compared to Europe. We American love our cars and our cities don't have the efficient Rail systems currently in place in Europe. We too have roundabouts, but usually only in places with fewer cars.
Per Hultman There are places where roundabouts simply wouldn't work with existing roads without massive reconstruction. And running a train througn a roundabout simply wouldn't work. You find economical solutions for problems. We do use roundabouts when they are practical, but when a road system hasn't been built around them, just adding them in doenst work.
Except that, in so many places, we're now putting traffic lights on the roundabouts, too. Roundabouts don't solve everything.
Per Hultman - I might agree with you if it weren't for the idiots who refuse to slow down.
That's the reason for traffic lights........the idiots.
Let's play a game. Scroll down the comments and take a shot every time someone says "roundabout".
haaaa
oncom put stuff
Get to the point versus roundabout
I just died of alcohol poisoning.
myowncomputerstuff I am already plastered.
is that a shot as in liquor
or a shot as in gun ??
I am never quite sure with Trump followers
Anyone asking about roundabouts needs to realize in Lacey there are TONS of roundabouts. They utilize the roundabout.
Was a bit confused there fora bit as it cars were driving on the left, but then then realized that's only while in the interchange itself. They'll definitely need the lines on the roads until folks get used to it.
Kelly Rayburn I've driven through one in MN, and they are extremely easy to navigate.
Two roundabouts at either end of the bridge. No traffic lights, no confusion. You guys in the us should really try it.
I went through a DDI once, and it made no sense to me. I was like "why drive in the left side?" But now I get it!!!
Looks like a nice addition to all of the roundabouts in the area.
As a local I look forward to this helping the traffic there.
They are doing the same here in Ephrata Pa.(322/222 interchange) Completion is expected fall of 2021. Now THIS VIDEO VERY MUCH explains what is going on! Thank you!
It's an intriguing concept, very thoughtful. But I wonder: does it ever snow in Washington state? What happens when there is a layer of 5 inches of snow on the road, just enough for the road paintings and curbs not to be seen anymore? The locals will be familiar with the unusual traffic routing, but what's with non-local drivers? I would be afraid of many wrong-way drivers in bad weather conditions.
We do occasionally have snow in this part of the world. DDIs are configured so that cars are aligned in the direction they need to be going and driver’s don’t have the sense they’re headed ‘the wrong way.’ DDIs are found in many parts of the country that have more severe weather than western WA, and we are not aware of motorists in those areas having problems being properly oriented as they drive through them. We will also have overhead signing that will direct traffic.
wsdot this idea is Guineas it should be take over to Europe :-)
@wsdot, this is a good idea but what about the roundabout? Wasn't that considered the most efficient way of handling traffic? They said that congestion is reduced to almost 60-70 percent?
no doesent snow often i live in lacey
In the heavily populated areas of the state (Seattle at least), everyone freaks out and simply parks on the freeway with the slightest whiff of snow....strange as that is it should mitigate your considerate concern. :-)
I think this is a truly brilliant, innovative design for an interchange. In fact, somewhere in my cubicle I have an article posted on the Springfield, MO DDI! The only real gripe I've heard about them is that they can be a hassle for some emergency vehicles in certain situations.
We got one of these in Saskatchewan and everyone is confused including myself, although it's a long ways away from where I live. This video does better than any other I've seen to explain it.
We have them here in NC as well. The traffic backups at them are worse then the straight aways they replaced, and add to them the confusion and they are nothing but an absolute cluster
Great video. I'd love to see a simulation of heavy traffic volume run on the DDI vs the current intersection. It would make for some good RUclips watching and allow people to get a real sense for how much more efficient the DDI is at handling large volume.
Americans, driving on the left side of the road? WHAT IS THIS MADNESS!!!!!!
connor escue I used to think so too, but this vid helps me understand.
Indigo 132 yeah I know. same with roundabouts in europe they work pretty well. I was just being funny
connor escue ok
It are just single lane roads in this case. What they do on the other side of the fence is not 'your' problem :-)
connor escue exactly !
Awesome! We just had one open in Saskatchewan Canada & driving it for the first time was a real treat!
This is really cool engineering and the video is really good at showcasing the intersection with a clear explanation and even a drive thru preview. Great work all round.
They just need a magic roundabout.
THAT would be absolutely a terrible idea.
G stone Hey, it's magic.
Ha ha lol
Dovenpeis other than Swindon and High Wycombe, magic roundabouts are pretty rare, but awesome😁
In the Netherlands we use "Turbo roundabouts" for these situations
In the Netherlands heavy traffic is more than 5 cars on the road at once. A roundabout does not work under the sheer volume of traffic a typical American city has where literally every family member has their own car in many instances.
@@mycroft16 Maybe the problem are that you have too much cars.
Bicycles for fatso meritards exist.
@@ElectricityTaster that's exactly what I said. We have a crap ton of traffic. No need to name call either. Ad hominem is almost always a sign of a lack of a cogent argument.
Keep in mind the population of the Netherlands is 17.8 million. We have cities larger than that. Total population is 330 million. Most families own 2 to 4 cars. The problem is a very fundamental one... European cities were built when everything had to be walking distance. Neighborhoods function as complete cities with all the shopping, markets, etc easily walkable by residents. Public transport was built into your cities in the form of carriages, cabriolet, etc. That just evolved into cabs and busses etc with time. In the East our cities started out that way as well, very European. But there was significantly more space here. It would only take 4 Los Angeles to equal the total land area of the Netherlands. And the population of LA is almost exactly the same as the Netherlands. That is how much more spread out we are here. With that many more people and that much more room public transit becomes problematic. Many people ride their bikes to and from work and stores all the time. Many take trains and busses. In NY thats the only way... only cars on the road are cabs and services (mostly). The car was invented here and it allowed people to go from their A to their B directly on their time table with any stops they wanted. A bus follows a route that only gets so close to your B and only at set times meaning allowing more time for route and getting to and from stops. America runs at a very fast pace. It causes some who visit anxiety. Saving time and going exactly where you want when you want well out of the range of a bicycle within time you have available means lots of cars. Which means different infrastructure to handle them. We have roundabouts. We know how to use them. We also know where not to use them. Even the Arc do Triomphe roundabout in Paris doesn't see the levels of traffic that typical American freeway to surface artery interchanges see 2x a day. So you're dealing with a very different culture of travel, much larger cities slread over much more area, and just life in America in general.
It is not as simple as plonking roundabouts down everywhere or everyone riding bikes.
@@mycroft16 MEEERICA, FUCK YEAH!
@@ElectricityTaster Thank you for that detailed rebuttal and analysis of the cultural and geographic comparison I put together. If you're going to be a little shit could you just keep your mouth shut and let the adults do the talking?
3:31 I like taking taking long walk in nature. This spot in particular is awe inspiring. 6 road lanes pumping fresh air into my lungs and 4 motorway lanes making noise like birds while I wait 4 traffic phases to cross this beautiful place ❤
I live near Springfield Missouri where those first ddi's were built. We have several in Springfield now. I confess I had my doubts when I saw the design, but having driven on them for several years now I want to tell you they work very smoothly and really do help the flow of traffic.
I was forced to drive through that intersection in the old days and worry about the traffic and being in a pileup from an inattentive truck. The new interchange there was an amazing improvement. There were days that the traffic was a mile backed up.
Seeing how this works from above looks great. Visualizing it from ground level will take some time to adjust. It's difficult to be confident in your driving when you always drive on the right then suddenly transpose to driving left. But I would like to try this out.
The roundabout would have *less conflict points,* and no need for the traffic lights :-)
Multi-lane roundabouts don't work so well when volumes are very high.
DDIs and 'Merry-go-Rounds' have a learning curve that many have not listened to!
By the time I began attended Saint Martin’s U in 2018, this interchange was only 2 years old. I started using it often, n I gotta say. I like it. It’s quick, with little wait, n you get to experience for like 10 seconds what it’s like to drive in Europe on the left side.
One frustration I can see is using the interchange at times of low traffic volume, such as at night, when in some states it is legal to turn left across an oncoming lane if the road is clear. This makes for a typically free flowing interchange. But now with traffic lanes crossing each other, you are still required to stop...even if there is very little traffic.
Isn't it always illegal to turn left at a red light without stopping? These interchanges all have signals to direct traffic. You're really reaching with this complaint.
My concern still centers on the fact that free-flowing traffic in both directions on the non-freeway road is impossible, as the signals cannot be green at both intersections for both directions simultaneously.
That's an excellent point. I suppose the benefits do outweigh the minor negative aspects.
Plus you can add sensors that signal the lights to change if they detect a car approaching during a low traffic time.
Yeah, lights would definitely be priority controlled during the off hours. Easily.
Brilliant. Modern design really shines through thanks to the video's look and feel. Hats off to the traffic engineers, and the animators, on this one!
@John Williamson Bummer.
@@johnwilliamson3752 Looking pretty is not a priority when designing interchanges, so saying it's ugly is is a weird argument. It is definitely not confusing at all when you actually drive through one. Green means go. Red means stop. Stay in your lane. That's it. It's simpler to drive through than a typical intersection and traffic flows much smoother and quicker, which is why they're being built in a lot of places. This design eliminates the need to yield to oncoming traffic when making left turns.
I actually drove through one of these and it was designed in such a way where it was obvious where you should drive. I was impressed.
We just got one of these in North Carolina. I knew it was coming a year before and looked online to see ho it would work so I'd be ready when the time came. When they first opened it up people got confused because not all the signs were in place, so people complained. But once they were in place and done, it took a few times to et used to it and the traffic has been flowing really well. Much better than it used to.
Neat. Now if we could just get ramps from EB SR-18 to SB SR-167 and NB SR-167 to WB SR-18. I would like the name of the person who designed the intersection of two freeways and left two of the on/off ramps out.
YES!
And anyway, it's too late by far. Two lanes each way on 18 are two lanes too few. And don't start me on the Port of Tacoma ramps to I-5. Never designed for trucks.
Yes please!
This video is really helpful
They recently installed one of these down here... I had no idea about the name but can attest that traffic flows so much more smoothly, thanks for the vid !!
We got one not too long ago where I live and I will admit I was a bit skeptical at first but in the end I really like it. It is very smooth and virtually impossible to accidentally go the wrong way.
The downside? You cannot continue straight if you're on the access road, you must turn, U-turn, and turn again. It annoys me that they don't mention this.
Well, most intersections don't let you do that anyway. Although, I will say that if you do need to go straight, then this particular model wouldn't work, unless they added an extra light for the exit to be able to go straight also.
If this represents a more cost-effective design that encourages better traffic flow and eases congestion, it's worth a go. Improved flow for cyclists and pedestrians is also a good thing, as we should be accommodating transportation choices. I'm just not clear about whether this is a one-size-fits-all sort of model, but I didn't dive deep into the details....it seems like planners and engineers would want to be selective on where a design like this is the most effective. I guess the studies do that revealing. Any new ideas and outside-the-box designs are needed in western Washington due to the horrific stress transportation systems are under and geographic limitations. Arguing about light rail for 40 years before a shovel went into the ground certainly didn't help matters, but that's a discussion for another day.
These DDI's have been in use in MO for over 7 years. As the video said the one in Springfield, MO, plus there are more throughout MO. I would not think they would keep adding them if they did not improve traffic flow. After putting 1 or 2 in then would see if the improve flow, if they did not why build more.
Indeed. I live near Springfield, MO. When they put the first DDI in place, it looked and felt like an entirely different road. The mile-long backups disappeared except under *EXTREME* conditions - it was more like a standard stoplight worth of backups. Not perfect, but an excellent stride towards high efficiency traffic flow, while minimizing cost and space requirements.
This is the most mildly interesting thing I've seen in a long time.
Congrats on being the most popular WSDOT video!
I'd be interested in how a large roundabout interchange would help or hinder vs this new concept.
+Jean-Pierre White . This is not a new concept, saw it Europe in 2003 somewhere between France and Spain, and before that in Monterrey Mexico in 1999. Down there they have both this type and roundabouts and they both work great as far as I remember.
But up here in the States we simply don't get roundabouts and I don't think we will easily get this design either. We are stuck with 1950's designed highways and overpasses, just as we are stuck with the pseudo-imperial measuring system even though metric is so easy and friendly!
Mia Lara You are probably correct about the US being resistant to different road layouts and traffic controls. I believe the reason is that the US driver has to date been conditioned to let traffic lights control traffic flow requiring no responsibility in their part. faced with a roundabout the drivers have to take responsibility for traffic flow, and if you have never done that or been trained to do so then there is a natural fear and resistance to traffic systems that differ from what is considered normal.
This is exactly the problem. Key example: any 4-way stop.
I live in an area with 1 decent size roundabout, and 2 smaller ones, and then another one that I frequently drive by. They are easy to learn but from my experience driving them, most people aren't comfortable with it.
Then you have the people who ignore their stop or yield sign, can't stay in their lane, etc.
I'm surprised I have never seen more accidents in them, but I've been in a few close calls because people weren't paying attention.
The one further away from me, about a year ago had a tanker semi flip going around the circle because he was going too fast.
Roundabout interchanges are in trouble, they are even getting dropped in Europe. This is because (despite what people think) roads aren't that expensive. Highways and freeways aren't that expensive. The real expense with this sort of infrastructure is bridges. They are hugely expensive. Even when creating a new interchange roundabout interchanges just aren't that cost effective, that's why in europe new interchanges often just go with dumbbell interchanges instead.
If they had the room, how about smaller over/under passes where the opposing lanes cross over each other. That would remove two lights and a couple conflict points. It would also eliminate confused drivers from being able to go the wrong way into oncoming traffic.
Downsides: It would certainly cost more and maybe obstruct visibility?
That would require a huge amount of space. You would have to start a lot further back to get one lane to rise up high enough to go over the other and then back down again on the other side.
anchskier That was the one aspect I didn't know the answer to.
+badlandskid
It is nearly impossible to go the wrong way on a well designed diverging diamond. I wouldn't worry about that at all.
Way way WAY more expensive
exactly, hear the words "well designed"
I'm definitely going to try this for my city great idea thanks for the tip
Driving along at 2:30, experiencing the interchange when suddenly a picture covers my windshield until I'm through the interhange. My first instinct is to frantically roll down the side window to stick my head out to make certain I don't rear-end a 1990s survivor Honda.
Why not a roundabout?? No lights and constant flow of traffic
Just a horrendous free-for-all. About as logical as 4 way stop intersections.
Myth busters did a test on roundabouts....find the episode and watch it....and its not a free for all
The large town where I live in the US is about to get it's 4th. There have been absolutely no issues except when a nearby, traditional intersection creates a backup into the roundabout during the busiest hours of the day.
my home town had a round about so i am comfortable with them, they work great until drives who don't know better yield to traffic entering the roundabout. once drives start slowing down unnecessarily the benefits are minimized.
In the UK they would stick traffic lights at every entry point to the roundabout, so I'd much prefer a DDI!
This is great for traffic flow for both Ped, Bikes and Cars! Great to see! :)
The first time I drove through one of these I was confused. But when you think about it and have it explained it makes a lot of sense. It takes getting used to but they do seems faster.
This was adopted in Springfield Missouri, a pioneer in the Diverging Diamond.
It is GREAT! It moves a lot of traffic much faster; there are no more left turn lights onto the freeways. Less lights to wait at.
Now most of our interchanges are using this system.
It is a little disconcerting the first time, but with well marked lanes it is a breeze.
But what if you eg. took the wrong exit and just want to drive straight onto the highway... can‘t do that here...
A roundabout would be better
Also driving on the left side of the road might be very confusing for some drivers especially older drivers. Furthermore, during nighttime this is actually very dangerous, the light might dazzle other drivers since it‘s not made for driving on the right...
This was all addressed in the video. The barriers prevent the light distraction, and very clear signage and arrows make it clear where to go.
BASICALLY THIS IS CITY SKYLINES IN A NUTSHELL
That is a really innovative solution to a common problem in so many areas.
We have a DDI in Pretoria South Africa and I must say it makes traffic a breeze, it just works and traffic flows and its easy on your gas spend too. DDI's are the best
I think unless it's a low traffic area, pedestrians should always be separated from traffic. Both for safety and lessening delay for drivers who have to stop for them.
Pedestrian (and other sidewalk user) access requires at least four
crosswalks (two to cross the two signalized lane crossover
intersections, while two more cross the local road at each end of the
interchange)
Meaning they only cross when a particular section is stopped?
Correct.
There are pedestrians in the US?
Xerdoz Lol
How does this improve wait times, when Free-flowing traffic in both directions on the non-freeway road is impossible, as the signals cannot be green at both intersections for both directions simultaneously?
No more left turns. And 'right turn on red' on both sides.
As for the flow, think of Manhattan. Fill up the middle section from the motorway. Wait for it to clear, then fill up from the side road. Everybody has to stop on the bridge, but in the end the volume is higher.
I don't see how this makes any sense unless the majority of the traffic is making left turns and even then only one direction of traffic gets a "free" left turn.
Tyler D. Merging? This Intersection? THERE ARE LITERALLY NO MERGING POINTS FROM EITHER TO AND FROM THE HIGHWAY.
Very impressive, really. Explained very well too :D
I'm looking forward to driving on that and seeing how it works, if any area in town needs it Hawks Prairie is it. It's already super busy there and growing like crazy.
The intuitive PROBLEM with this system is that, for a short distance, you have cars driving on the wrong side of the road. Drivers expect to see cars going in the opposite direction on their LEFT, and certainly not on their RIGHT. This might cause some confusion. It would be far better to put a visual barrier between both sides for a short distance to eliminate the problem. We are not British, after all.
That's why they have concrete barriers at those points to help alleviate that confusion...
Yes this exact problem is addressed in the video.
Not to mention the pedestrians and bicycle riders that are going to be in the center between two lanes of fast moving traffic.
Good job explaining it but there are problems. 1 when ice and snow cover all of the arrows and lines things won't be so simple. Also in areas where there is high tourism there is a great opportunity for confusion. While i think it will work, don't think it is a perfect bed of roses.
The high walls are supposed to mitigate confusion. Like blinders on a horse.
But the walls also take away any chance to spot red light violators and emergency vehicles. Even the police MUST wait for the green light, or risk wrecking their patrol car.
todd Brewer I've driven one of these in MN. Just like in the first person view drive through in the video, the DDI was extremely easy to navigate, with no real confusion at the crossings at either end. From the driver's perspective, there's almost no chance for anyone to inadvertently go the wrong way. From talking with a local resident I met there, he said that one change shaves about 5 minutes off his commute compared to the traditional interchange that use to be there. I welcome our new DDI overlords. lol
Okay, I kind of like this bridge design but you do have a point there. It's definitely something they need to improve upon before going through with this project.
Anchorage Alaska is putting in one and I don't think they thought it threw. Many people who come threw Anchorage are from out of town to do some shopping. Large numbers of tourists in rental RVs also add to the mix up. While I think it is a very functional concept it is just over kill for Anchorage.
Two words: Overhead signage. It's not that hard.
I can't believe this is the second time I'm watching this.
We have one of those here in Wyoming. It is a brilliant intersection. Works beautifully.
Roundabouts so old, lets think about something new we can sell...
No way. We still want circular intersections.
But they're so 1994.
Uhm.. the conflict-points thingy:
those numbers are not for the topology that is shown in the image.
And of course road-markings, signs, barriers etc - yeah, it is not like those are for all roads, only DDI can have those features.
And DDI has drawbacks as well - like an rather extreme reduction in bandwidth for those that want to go straight.
Cause now you have 2 areas in which the main traffic flow intersects with it self - that is a horror if at any point a congestion occurs as it multiplies its severity.
There are several of these in my area. They are the most counter-intuitive and basackwards road setups ever devised. As Der Yeti notes, unless you're a local who's familiar with the thing, and unless road markings are PERFECTLY maintained, American drivers' instincts to keep right of all traffic obstacles (as explicitly instructed by nearly every state's drivers manual) will get them into a head-on collision, simply by by driving "safely" in bad conditions. Also, and possibly more importantly, a pedestrian (let's say someone walking a baby carriage) must cross traffic lanes four or six times in stead of once or twice, AND *must* walk between two opposing lanes of traffic, typically with nothing more than a Jersey Barricade between them and multilane traffic on both sides. It's as if traffic engineers are doing everything the can to discourage the use of non-motorized transportation. Also, the insanity of the design makes people avoid that intersection, only compounding the greater-area traffic congestion that the Diverging Diamond is supposedly trying to alleviate.
Common sense and logic both point to the same thing: A little "eminent domain" and a self-explanatory cloverleaf are the best choice for everyone.
We've got one of these here in Colorado Springs, I tell ya, it works wonderfully.
Drunk drivers and old drivers get confused enough. I foresee some crashes at these intersections.
You just know, those Under the Influence / Confused drivers are going to go straight through, they'll freak out, loose control and drive into all those pedestrians and bicyclist making there way down the center of the overpass. The only way I see these things working is if the state slows traffic down. You know it could be a new method of population control, most make it through some don't. That was awful dark of me. Sorry
People should *not* be driving drunk or high at all!
Gammareign but they do, so it's a concern that should be addressed
Gabendini - I agree that drunk/high drivers should be addressed - and removed from the road, not accommodated
Why not just use roundabouts?
zh11147 from what I have read on the topic, roundabouts and intersections with the least amount of rules are the most efficient. The speed is dependent on the size of the roundabouts.
Not what I had in mind, especially since this one requires a lot of space, but this design does seem more efficient (There's a smaller version of something like this here in Slovenia and it works great). ruclips.net/video/XDDmE4qoCns/видео.html
One of the things, that I find problematic about all of these "central planning of transportation" ideas, is preferential treatment. Here's what I mean by that: decisions of the use of space determine quite a bit of human behavior. Highways and large rings around the cities, for example, coupled with the commercial zones, can totally disrupt commercial activity inside the old city center (lots of examples here in Europe where the central planers took the modernist approach to zoning and urban planing).
Don't get me wrong. I'm not against DDIs per se. Sure, DDIs might solve certain problems but at the same time create different problems, such as the questionable pedestrian and cyclist safety, perhaps even due to increased speed of the traffic flow. This is also the reason I tend to favor smaller roundabouts and more deregulated traffic arrangements, since they tend decrease speed and increase safety as well as have a more "natural" flow, of traffic, which can, if not to great, be always in movement. Of course this ought to be coupled with deregulation of other things as well, especially zoning and other things.
Also, don't think that I'm against highways or higher paced transportation. Not at all. Everything has its place, if thought out well... but more aspects of travel ought to be taken into account when designing things overall. ;)
I guess what I'm trying to say, that whatever it may be, that one makes, should at the same time improve the problematic thing without taking away ways that were possible before. Something like that.
zh11147 Actually a roundabout would be way more efficient here and help to speed up traffic. Only idiots wouldn't be able to navigate it.
This is a stop light intersection. Pedestrians have dedicated cross walks with push button to request the go-ahead. It's no less safe than any other standard low-volume cross walk. Pedestrians are very low volume at all overpasses like this in the U.S.
It works!!! There is one up the road from me here in Colorado Springs. So much flow during rush hour.
I don’t know why the hell I just watched this but I’m glad I did. Hurray for infrastructural ingenuity!!!
People who say Americans are stupid because they don't know how to use a roundabout, is almost like saying a brit is stupid for not knowing about turning right on red!
Ryan Morris
Ever drive a semi through a roundabout, Limey?
Turning right on a red when the rule of the road is driving on the left? Sounds a bit dangerous to me.
bcubed72. Works OK in Australia and there are some mean big wagons in Australia even semis with a hitch on the back.
Yes. As do hundreds of thousands of drivers in the UK every day.
Ryan Morris I think you forgot that Britain is a right-hand drive country...
What's wrong with a roundabout?
remember, this intersection still has traffic lights. So a round about with traffic lights is the best
A round-about also allows through traffic to go through smoothly, & right lane cars to divert off without going through the round about just like this DDI, it also eliminates need for a left turn lane, basically does everyhting a DDI does.
But a driver can be stuck on a DDI red light even if their is no traffic or less traffic on the other road. While the round-about driver on a red light is allowed to steal a right turn is there is little of less traffic in the round about. And since it's a round about, the right turn can be used for a left turn as well as a U-turn, pretty cool.
I used to see good traffic management at Bloomfield - orchard lake round about in Michigan sometime back
Matt Dathew I don't think he knows what a roundabout is...
In simple understanding, it's just an intersection with a circular island in the middle
Yeah, now add 3 lanes to it and a volumen of tens of thousands of cars per day. Oh, plus the intersections less than 100 yards down the road aren't roundabouts so when they are red, traffic flow through the roundabout will stop. how does that work out in terms of right of way when it's trying to clear again. Oh, and then stop up 3 minutes later when the interchange down the road cycles again? Yeah... roundabouts do not work on busy interchange complexes like this unless EVERYTHING is a roundabout and that come with its own special problems.
We have one of these to get on the Glenn Highway in Anchorage. I t works very well while reducing the potential points of collision
Wow. Great and impressive idea. Thank you very much for sharing this usefull invention to the world.
what happens if a car on the road gets lost?
The driver loses their licence, on the grounds that they're too stupid to drive.
mrgilbe1 Not in America they don't. Here you can kill other people with poor driving an dininished mental capacity without losing ot your license.
In contrast, in Illinois, ifi you have a chronic illness that has a very low probability of causing loss of consciousness, and most people with that disease are well managed on medication, even if you have a decades-long perfect driving record, you need a doctor's letter every time you get your license renewed.
Dr. Steve Brule Send them back to Europe, let them start over. ;=)
You call your friend Carlos ?
The way they design it, when you come to the crossover, it feels like you are at a standard + intersection with one-way streets, and the only allowed direction is straight. It is because of the angles they use at the crossover. So unless you turn at the intersection, you will be on the correct path.
why dont you use roundebounds?
because you can't build a roundabout in midair or over a major highway without a far more massive cost.
We do all the time. We don't just put them anywhere, we actually plan our roads and try to make them cost effective.
This is the freshest CGI I've ever seen from WSDOT.
There gonna love that interchange. I-55 & WEBER RD in IL near bolingbrook/romeoville needs one.
I suppose most people can adapt, but we have been getting traffic circles and there is always at least one idiot that has no clue when you go through them.
: ( I, admittedly, am that one idiot.
You are overstating the benefits. The plan (1:59) purports to show 26 points of conflict. 8 of these (4 crossing, 2 diverging and 2 merging) are not real. They exist only if traffic is allowed to leave the freeway, cross the other road at the intersection and return to the freeway IN THE SAME DIRECTION. Nobody does this intentionally, but if it's a problem the movement could be prohibted by changing the arrows and line markings at much less cost.
In fact the change reduces the conflict points from 18 to 14.
Furthermore, although the number of conflict points is less, the number of conflicting movements is MORE. All traffic turning left still has to cross all traffic going straight, but now all the traffic going straight (east-to-west) has to cross traffic in the opposite direction (west-to-east). TWICE.
I'm excited that these are coming to Washington State!
While I am a big supporter of roundabouts, it's really obvious that there are huge cost benefits for DDI's as they can fit into the existing bridges and ramps that are commonplace in the USA
Why not build roundabouts?
Roundabouts are a good for lots of situations, but they don't allow traffic to move as quickly or freely as a DDI does - especially in high traffic situations. They also require plenty of space (radius) to account for turning semi trucks. Additionally, there's lots of wasted (read: non-drivable) space at the center of roundabouts - good for aesthetics, but not for maximizing traffic flow. My impression is that in this case, space is limited due to surrounding development, so a DDI is a good way to minimize additional space requirements and maximize traffic flow in peak hours.
-Civil Engineering student at Missouri S&T
Joe, thanks for stating about the Semi tractor-trailers in roundabouts, as an experienced driver myself have encountered a couple of poorly thought out roundabouts in both commercial and personal vehicles. There are some without the central greenery which do have markings for large vehicles to use as if it was also a 4 way. But then again even that design still confuse too simple minded one tracked individuals who never seem to pay attention to the signs showing the use.
Snoopy Schulz We don't have any vehicles with less than two axles.
Our typical semi trucks range from 45-73.5 feet long (14 to 22m). In order to accommodate semi trucks, roundabouts would require a diameter that absolutely exceeds the current intersection size... The MINIMUM turning radius for a full-sized truck is 75 feet (23m). So that equates to a diameter of 150 feet (46m). See Figure 7-5 here in our typical design standards: onlinemanuals.txdot.gov/txdotmanuals/rdw/minimum_designs_truck_bus_turns.htm
On top of all this, keep in mind that this intersection is in a busy and growing area. So a roundabout would have to have multiple lanes - probably two main lanes and then outer "fixed" right-turn-only lanes, which would likely be protected by a concrete curb. All of this said, the minimum diameter with two lanes that accommodates tractor trailers would be 150 + 10*2 = 170. Without outer right-turn-only lanes, it would be even more. Possibly nearly 200 feet in diameter in some places.
Sorry, but I can't see where you're coming from in this situation.
Joe Collum
blah blah you too stupid to roundabout end story
Snoopy Schulz I sincerely regret spending 20 minutes researching and informing my comment to you. Go read a book and talk nicer. Goodnight.
A two-layered bridge would have even eliminated the two crossing points of the DDI at 2:06. On second thought, the number of conflict points is not correct, because the number of separate lanes is not considered. Actually before DDI it's 40 (26 X-ing, 8 merging, 6 diverging), with DDI at least 31 (21 X-ing, 7+ merging, 3+ diverging, see at 1:28). The number of crossing points the two-layered bridge would eliminate is 15 - at probably higher costs.
Another possibility, two two-lane round-abouts with separated right turn lanes or one big round-about bridge, would have only 12 conflict points (4 X-ing, 4 merging, 4 diverging) with a 2+2-lane bridge, 16 (+4 X-ings) with a 3+3-lane bridge. This had the advantage of not needing any traffic lights and therefore keeping a better traffic flow.
I have another more basic solution: use the subway instead of your car - or is this idea too European? Greetings from Germany!
Naja. Eine 2-Layer Brücke ist dann doch etwas teuer. Und das Problem mit dem ÖPNV in den USA ist folgendes: Das Netz is sehr schlecht ausgebaut, du kannst dich freuen wenn du einen Bus hast. Klar, in Metropolen wie New York oder Chicago ist das eher weniger ein Problem, aber so ein dichtes ÖPNV Netz wie in Deutschland findest du selten, soweit ich weiß. Correct me if I'm wrong.
No subway too expensive. Too much area to cover and not enough population to warrant it.
The US used to have a strong rail network, but the auto and oil industry lobbied to have them shut down because they were too efficient and hurt auto and oil sales.
Money is always an issue. The proposed solution is probably the most cost efficient and time efficient. It takes advantage of the existing bridge and roads, and simply reroutes traffic. That's much cheaper than building a new, two-layered bridge.
As for subways, this is in a town of 45,000 residents. It's never going to get a subway system.
Using the subway only works where there is a subway. What works in Europe won't always work in the US and vice versa because we are different countries. The US is a VERY car centric culture where many families have a car for everyone that can drive. That can be 3 to 6 cars per household. We have a LOT more cars on the road than Europe. Your idea of traffic is, quite frankly, hilarious. The Katy Freeway in Houston for instance has 26 lanes. There is that amount of traffic volume on a daily basis that it needed to be that wide. Cost is also a factor. How much is the city willing to pay, or the state, or the tax payers. Bridges ramp the price up exponentially and have long term maintenance costs. Consider further that a roundabout is only as good as the interchanges around it. If the flow is stopped by a traffic light 100 yards down the road, then a high volume roundabout is going to screech to a halt every 3 minutes when the surrounding lights cycle, often not in sync. That's going to throw right-of-way to the wind and create utter chaos.
Before you make a suggestion, attempt to understand the entire situation.
There is also a DDI Interstate 435 at the Front Street exit in Kansas City, MO and another one at Interstate 270 exit Roberts Road in Columbus, OH. I have personally been through both of these numerous times.
Went on a DDI in Atlanta. For a fleeting second I felt that America was *finally* driving on the "right" side of the road.
Is the US that resistant to roundabouts that you'll invent a whole new kind of junction to avoid them?
mellonians Where roundabouts would be most useful in the US are in high density urban areas, where there isn't sufficient lane width or approach area to implement either roundabout or diamonds without condemning high rental properties.
rp
Shame they're not bright enough to use roundabouts
I wish ConnDOT would make videos like this. The DDI looks intriguing!
I like these and roundabouts both we have both in Joplin Missouri
Tending towards a roundabout...why not just make a roundabout, or perhaps two, then you don't need the signals or to stop traffic at all?
Exactly my thought
roundabouts are a good idea in theory... in practice people dont really respect the right of way and its impossible to enforce... plus roundabouts of more than two lanes are more trouble then theyre worth
+Lone Wolf Well, the main issue may be that people don't know how to use them. Having more of them will make it harder at the beginning but will help in the end. In Europe, roundabouts are very common and people are used to them which makes them fast and safe. Roundabouts are very effective, therefore you need only two lanes where light intersection would need three or four for the same amount of traffic. More than that does not increase throughput efficiently and usually needs grade separation.
Jan Sten Adámek
in very busy surroundings people dont respect the right of way and cut off the people already engaged or crossing between lanes... like i said its impossible to enforce... i dont know of big cities who consistently use them... i know paris has the arc de triomphe but its a bit of a dinosaur
I'm not sure if you're joking here or not....in case you're not, a Multi-level interchange is very expensive, certainly when compared to this DDI. There's also the time required for construction, which is very disruptive to business and finally, it's not as ascetically pleasing.
Roundabout?
this set up is great we have here in Albany NY a similar set up called a S,p,u,i single point urban interchange which works exactly like a D.D.I but its has a "x" pattern to it
Cool ! Amazing Soluction!