4-way stops vs. roundabouts: which is more efficient? Mythbusters tests both (vid)
 

The "efficiency" question Mythbusters is looking at in this test is throughput -- which design allows more vehicles to use the intersection in a given amount of time. But that translates to fuel efficiency as well.

Drivers who have used both can probably guess the outcome...

http://www.youtube.com/watch?v=OvoFjirrgYA

I didn't even realize that "a roundabout is more efficient than a 4 way stop" is a myth. Maybe it's just a myth like gravity is. Or the moon landings.

I wonder if traffic sensing stop lights would make a difference for the 4-way.

It really depends on how well they're programmed. I have a bunch around me. Some work great, others make me stop almost every dang time.

Funny! :D

Maybe suspicion about roundabouts is a side-effect of general wariness (in some quarters of the U.S.) about things "European".

MythBusters must be running out of ideas, or something. Anyone who has lived in both the US and in Europe (me, for instance), will easily come to the conclusion that traffic circles are much better than intersections at passing traffic.

Was a bit unhappy earlier, because I could not see the YouTube video because OpenDNS (which I WAS using) blocked it as being a "video sharing website".

Maybe they did this myth since it seems so logical that traffic circles are more efficient than 4-way stops, therefore if proved false, it would be climactic.

Also depends on the design of the roundabout. Those which are designed to make traffic flow efficiently do just that, and do it quite well (at least in my personal experience). Unfortunately, some highway departments are staffed by d**kheads who design them to be "traffic calming" devices - with too small a radius, reverse banking, etc - to impede traffic flow.

I'll take a roundabout over a 4 way stop every time.

regards
Mech

Daox, they only sense you. They miss you! They want to spend more time with you! You two never talk anymore.

I think you're right. Many people I know would love them if they were labelled "American inventions". Nationalism is still alive and well here.

Freedom circle.

The utter madness of the US 4-way stop is that you ALWAYS have to stop.
Even when there's no-one else around ... but a copper hidden somewhere behind a bush or sign.
So everyone has to come to a full stop.
Always.

Mythbusters obviously tested the roundabout in what is its LEAST efficient operating mode : when there's lots of traffic coming from all directions.
In this case, traffic on the roundabout tends to hinder traffic getting onto it.
That's when they usually get additional traffic lights in Europe, if the road authority is smart, these only work during peak hours.

It surely would, if it means you won't have to stop when there's no cross-traffic.

But they still make people stop.

Unless traffic is pretty dense, you can time the arrival of another car on a roundabout, and adjust your speed to sneak in behind it, or in between 2 cars.

Must be something else I'd say.

I'm using OpenDNS name servers as well.
No issues seeing the YT vid
(OSX 10.8.5 , using Safari 6.0.5)

We have those all over (western Washington) and... no. Typically, the lead cars heading towards a red light will have to slow down and often stop before the sensors are triggered and the light turns to green.

In Anchorage, AK, they have timed lights and the prevailing traffic heads one direction through many intersections (basically, N-S south of downtown and E-W east of downtown). Because of this, they time the lights so you hit green lights at every intersection as you go through the city along the primary route. This works very well (probably even better than roundabouts)... until you try to take one of the side streets.

I love roundabouts, and we are starting to see them show up in Washington. Near my old house, there was one traffic light that I had to wait at for about 20 minutes a day as rush hour traffic slowly filtered through it (1+ mile backup every day). Once it was replaced with a roundabout, there was NEVER any delay.

When I went to England/Scotland, there seemed to be a lot of round abouts and in the well-poulated areas they had street lights. I *think* they only turned on at peak hours.

I like overpasses. Here in San Jose, most of the expressways are 50MPH. There are intersections, but when two E-ways cross, there is almost always an over/under pass. Then to transfer roads, there are auxillary roads to exit one and merge onto the other, usually in a 'U' fashion, but not a hairpin turn. They work really well, keeping traffic flowing at a steady pace. The nice thing about the auxillary roads is they give you a good excuse to have an office building or restaurant or similar.

Windows XP Pro SP3, running Firefox 24 and Chrome 30.0.1599.69, over a WNR3500L with DD-WRT, and an OpenVPN pipe to Canadia.

Nope, definitely was OpenDNS. It was an OpenDNS page that informed me of the blockage, the video was still blocked when I rebooted my router two different times, and once I went to Google's public DNS servers, the problem itself went away and I could see that video above.

I'm now using OpenNIC.

Roundabouts can be damn effective-but that relies on the people using it correctly:eek:

Over here (Glasgow), there's a myriad of roundabouts with full time lights..

at peak times this means significant tailbacks on approach to the roundabout

classic example here
http://goo.gl/maps/JEjwF

this frequently backs up on to the m74 motorway, and approx a mile up the a725 at peak times-hardly a beacon of efficiency

At other times the lights often means stopping for no reason (like a 4 way stop)

so they aint flawless:thumbup:

320touring, that's why, although roundabouts are effective at times, I prefer overpasses with auxillary roads. The only traffic congestion possibility is where you merge onto the next E-way, but the auxillary road is usually long enough to not effect the traffic on the first e-way if the line to merge gets too long.

I'll post a screenshot of the two expressways I'm talking about like you did as soon as I get home.

We have some similar situations here, although we're a touch shorter on land than you lot;)

there's no magic bullet though, unless of course drivers actually paid attention..

When I started driving here, there were "traffic circles" which were two lane roundabouts. They are nothing new as that was 45 years ago. As far as overpasses, they are much better for limited access roads with much higher traffic volume. The two lanes entering the Hampton Roads Bridge Tunnel can see 86,000 vehicles in 24 hours, on just the eastbound 2 lanes.
At 420 cars in 15 minutes, obviously a roundabout would never work for that kind of traffic volume. On US1 in the Florida Keys, I have watched people wait 15 minutes to make a left turn in very heavy traffic with no lights to break the flow. I would just go right and make a u-turn shortly after.
On my typical drive, which involves 46 lights in 40 miles, they could eliminate half of them and make those roads right turn only. At least they are decently timed, even though you have to go 3-5 over the limit to stay in the timing "sweet spot".

regards
Mech

Around here the biggest problem is that people don't understand what a "YIELD" sign means. Some think it means "stop". And some don't stop even when stopping is necessary. That tends to render the roundabout (AKA traffic circle) ineffective. :(

They are adding roundabouts all over the place around here. I like them.

Around here, ICBC, our public insurance company (monopoly), has a large say in road planning. I am told that traffic flow is less of a reason to use roundabouts than insurance reasons. It is far easier to determine who is at fault in an accident in a roundabout. Whoever is IN the roundabout when it happens is not guilty. Four way stop accidents are often less black and white.

5th ave rocks.

the AK drivers in roundabouts on the other hand...no really you don't have to stop to let me in, or stop for the guy who is, like you, just about to enter the round about.

Here's the "intersection" I was talking about. I think (from seeing it in action) this is the best option to eliminate intersecting traffic as much as possible. Both Almaden Expressway and Capitol E./Hillsdale Ave. are high traffic streets that don't see a lot of back-up from this intersection. It takes a lot more construction-wise to do this, but it alleviates congestion quite well. There are a lot of spots that have two routes onto the next expressway, not really sure why, but they help in traffic congestion (or lack thereof).

The pic might be small, see attachment:
http://i1289.photobucket.com/albums/...ps3e8e8db5.jpg

Dark Green: Capitol, West to Almaden, South
Light Green: Almaden, South to Capitol, West
Red: Hillsdale, East to Almaden, South
Orange: Almaden, South to Hillsdale, East
Dark Blue: Almaden, North to Capitol, East
Light Blue: Capitol, East to Almaden, North
Purple: Capitol, West to Almaden, North
Pink: Almaden, North to Capitol, West

Over/underpasses work well, if you have ample space for them.
Space tends to be more of a premium in Europe

On the local ring road, we're going from a pretty congested, totally unsafe traffic light controlled crossing, to a situation where 1 lane either way in an underpass has to cope with all thru traffic (halving the thru lanes), while local + in/outbound traffic uses a roundabout @ ground level.
I'm wondering wether that'll improve things.


Weird, as it worked instantly for me.
The whole idea of using OpenDNS was not having gov't mandated or whatever filtering.
I've added OpenNIC DNS to my list - now using OpenNIC, OpenDNS, Google, and my ISP in that order.

Tell me about it. Imagine wanting to look at the video at the start of this thread, to see whether the MythBusters crew would goof up their test procedures to the point where the test itself would be invalid, and getting that blasted "Daddy knows best" webpage instead of the YouTube video. I was not happy, that's for sure.

It's not just space, it's money. Look at the cost to construct an over/underpass, versus a roundabout.

A funny thing: my brother is the municipal civil engineer where I live. He's the guy who decides on things like traffic lights vs. traffic circles. He hasn't put in one in 25 years. We've talked about it. Part of the problem is we have an unusually high concentration of seniors who don't like/adapt well to change (my take, not his). Another issue (already mentioned) is roundabouts require more space. Another is they complicate snow removal.

Yet in the closest neighbouring small city, their engineer has been adding them regularly in the last 10 years or so, mostly on major roads.

Well, we do use over/underpasses here, when & where there's enough space available.
So they're not abundant, but we got some.

The Brits often use 2 bridges on Motorway entrance/exit complexes, with a big roundabout laid out over the Motorway.
That's also quite costly, but it has the added advantage of physically preventing people from going the wrong way on the motorway - whereas in Belgium the exit and entrance are often right next to each other, and relatively many people take the wrong one ...

Is that 1000 Islands in the St Lawrence ?
Not exactly your typical municipality :D


We have over 20% seniors.
They adapt better than some youngsters.

The latest annoyance in the UK is traffic lights on roundabouts, they are adding them everywhere! Whoever thought they are a good idea should be shot.

I just got back from a trip from Bend, Oregon, and they use roundabouts extensively. Since I don't often see roundabouts, it got me wondering how efficient they are. Good timing on posting this topic.

Under light traffic conditions, there is a good chance a vehicle won't even have to stop which will preserve the momentum. I wonder if that had anything to do with me getting the second best MPG to date; 35mpg in my 205hp TSX. Of course, the constant elevation gain and loss was the biggest contributor to this excellent tank.

Under ideal conditions, you get to flick the car right & left (or left & right, depending on locale) and have a lot of fun, too!

---

Euromodder: yes, on the St. Lawrence River. Not too many boat traffic issues, except on sailboat racing nights. :D

I have lived in NZ now for16years and love roundabouts, not only are they efficient even in heavy traffic areas, once everyone knows how to use them but they also save on electricity and maintenance. I grew up in North America without them, other then a few silly ones they added to slow traffic in congested neighbourhoods( Vancouver West end)which were just plain silly. In the Ottawa valley I noticed that they are starting to install them and when they first did this a few years back I could not believe the complaining on the talk shows and the crazy way people thought they worked. The way they first used them was very inefficient, a bit like a four way stop but only different. However last summer, three years on, I noticed that people are getting the hang of them and they have become very efficient as they should be. I aslo noticed that they are starting to embrace them. As mentioned by someone, my elderly Mother avoids them if she can. The other thing that should be standardized is how everyone signals on entering and exiting, What makes sense to me is if your intention is to turn right you singnal right just before entering, left the same, if you intend on going straight through no signal that way everyone waiting to get in knows what is going on. If there are more then four exits or you are doing a u turn you just live your signal on in the direction you are going until just before your exit then signal your exit. that way the guy waiting at the next exit can go and not sit there guessing.

This reminds me of the first time I encountered a roundabout when I was 17. It was late at night and I had a few friends in the car and decided to show off by going round and round as fast as the old Volvo would go. After about the 3rd go-round, I noticed a parked police car and an officer looking very intently at me. Rather than make him chase me down with the lights on, I just drove up next to him and rolled down my window to hear his lecture. "That reckless driving is a $$$ (I don't remember the amount) citation."

"Wow", I said. Then I drove off.

I might not speed round and round anymore, but it doesn't stop me from enjoying the flick right and left at speed :D

A typical Bend, Oregon roundabout
http://static.panoramio.com/photos/large/25190590.jpg

How Uhmericans do roundabouts
http://farm7.staticflickr.com/6136/6...5e4c9d5f_z.jpg

^ This ^

On my way to a job I had for a decade there was a light-signaled 6-way intersection. One leg out of 6 was coming from a large mall area 4 miles down the road. Constant turn-off-your-car-and-catch-a-quick-nap waits day and night (or accelerate to 70 to try and catch that infernal green light). Rush hour had mulit-light cycle backups on 4 legs. It was replaced with a relatively small round-a-bout and there is no back up with traffic... ever. The major leg from the mall area has 2 lanes entering the circle and everyone else has no problem getting in natural gaps or where those cars are coming off.

And the larger the circle... the more efficient the round-a-bout. The mythbusters circle was unrealistically small. No way you're getting a fire truck through that in real life, unless that center circle is just a rolled curb onto brick or more pavement. A larger circle can hold more cars and maintains higher speeds.

The ultimate round-a-bout is an interstate ring road around a major city. 50+ mph and no waiting. :D

Be careful what you wish for...
http://www.a5oc.com/forums/attachmen...roundabout.jpg

Search for "magic roundabout" to study the concept...

I think I may have heard of this one before. Is this the one that has round-abouts inside of round-abouts?

Duhmericans would be crashing every hour in that thing!