The Case for More Traffic Roundabouts

http://priceonomics.com/the-case-for-more-traffic-roundabouts/

by Oletros • 11 years ago

65 80 11 years ago

teilo• 11 years ago

There are two problems with roundabouts in America.

The first problem is the people who don't know how to drive. I cannot count the number of times I have seen people stop in the middle of a roundabout to let cars in, or stop at the entrance and stare in confusion when there is absolutely nothing coming.

The second problems is inherent in the design. A line of traffic that is going straight can, effectively, prevent any cross traffic from entering the roundabout, due to the small radius of most US traffic circles. This is a trade-off, of course, and is still safer than traffic lights or a 4-way stop, and usually more efficient.

monknomo• 11 years ago

The first problem is a problem with US drivers in general. I don't know what we should do about it, except perhaps test people's driving abilities more frequently. I, for one, honk at people who fuck up my roundabout experience.

I think the second problem is an acceptable tradeoff, but ymmv

Zikes2• 11 years ago

I see the first problem all the time, especially at stoplights. Often when there is a line of cars waiting at a red light, when it turns green someone will remain stopped so that a waiting vehicle on a perpendicular street or nearby business can pull onto the highway in front of them.

They think they're being polite, but they're forcing dozens of cars to wait for an additional cycle of the stoplight, whereas if they had just pulled through the light as normal then the waiting car would get a chance to merge as traffic either cleared or came to a stop again.

shkkmo2• 11 years ago

"dozens" is quite a bit of hyperbole. I generally only see behavior like this when traffic is dense and the speed of traffic is limited. In those cases, letting someone in doesn't decrease the number of cars that make it through the light. Additionally in those cases, it's quite possible that if nobody lets in the the car trying to merge, they will never be able to merge.

Obviously, optimal behavior is dependent of the traffic conditions.

jessaustin• 11 years ago

It seems that the slight inefficiencies you cite in the first complaint would eliminate the phenomenon described in the second complaint.

The point of roads is not to transport any particular traveler at the greatest possible speed, but rather to transport all of us in safe and convenient fashion.

dwc• 11 years ago

Interesting observations. As a counterpoint, there are a couple of roundabouts between here (Phoenix) and Las Vegas, notable both because there's often fairly heavy traffic and that almost everyone on the road is from elsewhere (and therefore unfamiliar). They seem to operate quite smoothly, and are a welcome break from waiting for several cycles of traffic lights.

I'm curious... where have you seen these troubles? Perhaps the small radius is the real issue?

aidenn0• 11 years ago

There are a couple of roundabouts where I live, and I see the second problem all the time. The best (worst?) was someone who came to the entrance, stopped, sat there for about 3 seconds and then went when there was a car coming in the roundabout and nearly caused a collision.

brc4• 11 years ago

Simple educations campaigns would solve the driver education issue. Get all networks to run ads with celebrities showing how to drive in a roundabout. You could throw in some non-texting message while at it.

The ignorance argument is difficult to agree with because every country has had to introduce them to an uneducated population at some point. You could have used the same argument against traffic lights.

sandworm101• 11 years ago

More, but only those little ones where the island is smaller than the road so that motorcycles can fly strait through.

davidw• 11 years ago

One of the odd things about moving from Italy (where they've had them for a while) to Bend, Oregon is that there are actually a ton of roundabouts here in Bend, for whatever odd reason. People seem to handle them just fine.

tomohawk3• 11 years ago

It was a revelation when driving through the UK that driving could be enjoyable again. In light to moderate traffic, there was rarely a need to stop. In contrast, in the US, it's stop/go/stop/go. Even in heavy traffic, the roundabouts were better in terms of throughput and safety.

msandford• 11 years ago

Roundabouts stop being useful once you get to "gridlock" style traffic, though. Because the traffic tends to work its way back into the roundabout and clog the whole thing up. I experienced that this spring in Scotland on a visit.

So long as the traffic flow is at least the double-digits (mph or kph) roundabouts are just fine. Below that though, and there be dragons.

People tend not to jam up intersections with stop signs unless there's a bit of space for them on the other side of the intersection. Same for stoplights, although there are some cases where traffic backs up into the intersection though that generally has more to do with people who are moving (albeit slowly) and then everyone jams on the brakes all at once, stranding several in the intersection.

toxik• 11 years ago

In Sweden we have a lot of roundabouts (and we also love to brag about having the world's lowest road fatality rate) -- what I see a lot for big roundabouts is traffic lights before entry. Best of both worlds.

JackFr• 11 years ago

That's the question I had. I had a very good experience with roundabouts driving around France for two weeks, but as a resident of Manhattan I wondered how they would fare under extremely congested conditions with many aggressive drivers. (I imagine they have those conditions in Paris -- but in Paris we took the Metro.)

Cyph0n• 11 years ago

I live in a city called Al Ain in the UAE. It's quite known for the sheer number of roundabouts. Due to heavy congestion at some of them, they've started replacing them with either intersections or roundabouts with lights.

How does congestion happen? A roundabout typically has four entrances. During peak traffic, one of these entrances might get clogged. This one side causes the other four sides delays due to right of way. Say a buildup forms at another side because of the delay. The other sides will be even more affected. This snowball effect is usually what causes congestion at peak traffic.

Traffic intersections on the other hand are immune to this issue because the delay depends solely on the light's timing, making it way more predictable.

laurencerowe• 11 years ago

I blame the stop/go/stop/go feeling of US driving more on the grid rather than the lack of roundabouts. 4-way intersections are relatively rare in the UK, most minor road intersections being T-junctions.

superuser2• 11 years ago

City planners are aware that continuous driving is enjoyable and go out of their way to eliminate that enjoyment wherever possible. It's called "traffic calming," though I'd argue the results are the exact opposite of calming.

Drivers who are comfortable, having fun, and moving continuously are much more likely to speed and get in accidents than drivers who are annoyed and constantly vigilant for conditions changing second-to-second (like stop-and-go traffic).

saosebastiao• 11 years ago

They missed out on the biggest problem with roundabouts: Their worst-case traffic behavior is cancerous. If any single exit is blocked, entry traffic will become blocked in all directions. And if the road grid is dominated by roundabouts, the problem grows in all directions.

It's not a problem when traffic is just congestion. It's hardly a common problem at all. But when it is a problem, such as is the case with a traffic accident that blocks multiple lanes of traffic, it causes full-stop gridlock to grow outward to the point of full paralysis.

The worst traffic jam I have ever been in was not in NYC, Boston, Seattle, or San Francisco, but rather in Idaho Falls, Idaho on a normally empty country road that was running parallel to the road where a drunk driver caused an accident that blocked the roadway. That single accident caused me and hundreds of other cars to sit in the same spot for almost 4 hours.

Marazan• 11 years ago

When traffic density is high you don't build roundabouts. Or if you do you then put part time signalling on them.

ksenzee• 11 years ago

But that's just the point. Traffic density should never be high in Idaho Falls. If you can break the grid to the point where people are in gridlock in Idaho Falls, you've done something wrong.

ileitch2• 11 years ago

One some larger roundabouts in the UK (and no doubt other European countries), they have traffic lights on the roundabout, between exits (I'm not talking about the entry lights). If one exit is totally blocked, these lights can allow traffic to continue out of other exits.

anon42• 11 years ago

One more problem is pedestrian crossings. With a traditional intersection, only cars changing direction cross the path of the pedestrian. On a roundabout, when you cross one of the exit arms, your path is constantly crossed by drivers going straight through, doing a right turn, doing a left turn and doing a U-turn. They are all driving at full speed too, rather than just starting from a stop. It is a delicate game where you gently put your foot forward to signal your intent, wait for the incoming traffic to stop for a moment, then dash to the other side. This is generally my experience, but maybe in other places drivers treat pedestrians on zebras differently.

mrb3• 11 years ago

"your path is constantly crossed by drivers going straight through, doing a right turn"

It's only crossed by the same amount of drivers than a regular intersection: those going on the same street as you.

"They are all driving at full speed"

Actually no, the curve of the roundabout (for properly designed roundabouts) slows them down. In fact a traditional intersection causes them to drive even faster since many drivers go in a straight line.

"It is a delicate game"

The nice thing about roundabouts is that you only have to check for cars coming from ONE direction, as opposed to a traditional intersection where cars can come from behind you, from your side, or from in front of you. So crossing a roundabout requires less cognitive bandwidth.

brc4• 11 years ago

You're wrong about pedestrians. The crossings are upstream of the roundabout and you only have to deal with two directions of traffic.

timthorn2• 11 years ago

If any single exit is blocked, entry traffic will become blocked in all directions Typically in the UK, if the traffic is this bad, then drivers on the roundabout leave gaps to enable cars going in uncongested directions to get through.

mrb3• 11 years ago

This "biggest problem" also occurs with traditional intersections.

In both cases, traditional or roundabout, drivers are supposed to leave gaps in the traffic to at least let some cars through the intersection.

In both cases, if drivers don't follow that rule gridlock will ensue. In fact, 2-3 cars stuck in the middle of a traditional intersection is often all you need to completely block entry and exit traffic by preventing anyone from going straight or making left turns: https://en.wikipedia.org/wiki/Gridlock

foobarian2• 11 years ago

In New York City the rule is "Don't block the box" and it carries stiff penalties.

I always found it funny how easy it would be to DDOS a roundabout. Get 10 friends together and drive around in a circle all day.

EdwardDiego• 11 years ago

Roundabouts are great, dependent on traffic flow. If you have large amounts of traffic moving in one direction, it will prevent traffic flow from the direction that has to give way to it. In New Zealand, we use a lot of roundabouts, but often congestion easing requires replacing roundabouts with traffic lights to merge two incompatible streams of traffic.

ileitch2• 11 years ago

I hear the argument "Americans don't understand roundabouts, therefore we wont build any" quite often in these kinds of articles. If you survey people about something they've never comes across before, of course you're going to get negative results.

If Americans can drive and talk on their cell phones, they can handle a roundabout.

maxxxxx• 11 years ago

There are plenty of them in Maryland. They work great.

hessenwolf• 11 years ago

Somebody gave me the argument in NASA that the US didn't switch metric because the cost would be too high because they are so big. Ireland and UK have gone metric in our lifetimes.

I mean, there are lazy people throwing out platitudes to justify doing nothing wherever you go.

tomohawk3• 11 years ago

If you asked farmers what they wanted in 1900, they would have said they wanted a horse that ate half as much and did twice as much work.

What they ended up with was a tractor.

jmount• 11 years ago

Small roundabouts do not work. Here in San Francisco the small ones (out in the burbs) jam up with few cars and are littered with minor car debris.

knz• 11 years ago

Obviously it will vary, but my experience in the suburbs of Minneapolis/St Paul (and driving in Europe and Australasia) has been the total opposite. Instead of stop sign hell every block causing gridlock during busy times traffic actually flows. "Minor car debris" likely comes from drivers who don't understand driving etiquette (use your bloody turn signal!) rather than road design.

timthorn2• 11 years ago

The mini-roundabout's success suggests otherwise: https://en.wikipedia.org/wiki/Roundabout#Mini-roundabouts

pmontra• 11 years ago

The most straightforward designs of roundabouts don't have a good safety record for cyclists. This post gives some hints based on the Dutch experience http://www.aviewfromthecyclepath.com/2014/05/the-best-rounda...

seanalltogether2• 11 years ago

Denver has a handful of growing roundabouts in newer neighborhoods, but unfortunately they keep installing them in all the wrong places. I'm convinced they are "testing the waters" by placing them in residential neighborhoods with very little traffic, which honestly just makes people annoyed by them, rather then appreciate them.

Roundabouts aren't a replacement for stop signs, they are a replacement for stop lights.

textingplan• 11 years ago

I remember when they installed one out in Littleton (suburban Denver) - it flows traffic spectacularly but it took years, maybe even a decade for people to get used to it.

I once came upon it and found a full size four door sedan in the (raised) island in the middle with four befuddled teenagers standing around shaking their heads. They had plowed into the traffic circle straight ahead, jumped the raised embankment and landed right in the center island.

brc4• 11 years ago

But the roundabout saved them. If they were not paying attention, as clearly they weren't, then they could have had a collision in the centre of an intersection. Better to end up in the he Center than t-boning a car.

knappe2• 11 years ago

Some of the most egregious roundabouts I've ran (heh) into have been in Aspen. They're right after you get off 70 (ie going 65/70 mph) and are often overgrown with bushes and trees. I'm all for roundabouts, I think when done right they're great, but I don't know what they were thinking when putting these in.

https://www.google.com/maps/@39.6439352,-106.3776606,248m/da... (2008 footage) https://www.google.com/maps/@39.6277372,-106.4200775,185m/da...

lisper• 11 years ago

That's actually Vail, not Aspen.

enjo• 11 years ago

They just installed a pair on the new Pecos bridge over 70. Those are really nice uses of roundabouts, so maybe we're starting to "get it"?

seanalltogether2• 11 years ago

Yes, I was going to mention the only one that really works well is that pecos roundabout since it's actually solving a real traffic problem.

brc4• 11 years ago

Light traffic residential areas are a perfect place for them. There's nothing more annoying than observing a stop sign in an empty road. I have roundabout near me and when there is no traffic on the roundabout you just drive through it. The residential roundabouts have only a slightly raised centre so you can drive through in almost a straight line.

Late at night when there is no traffic it saves having to stop at all.

foobarian2• 11 years ago

I wonder if it would be cheaper to install "Rolling Stop" signs.

shawkinaw• 11 years ago

I think the exact opposite, that four-way stops should for the most part become roundabouts, and that's it. And actually, just four-way stops between two-lane roads, once you start adding lanes it gets too complicated.

In Spain, basically everything is a roundabout, so much so that when the roads are big enough they have lights within the roundabout. That's way too much IMO.

spoiledtechie• 11 years ago

I love roudabouts. I've seen the great use of them the very first time I've used them. I've always thought of traffic patterns as being the largest time suck of our modern lives. Two solutions to this. Install roundabouts or take over the stop light manufacturing and production in America with a startup. Sadly neither have happened due to the large need of capital to make either happen.

ourmandave• 11 years ago

The Case Against Traffic Roundabouts.

https://www.youtube.com/watch?v=iAgX6qlJEMc

dazc• 11 years ago

You can't discuss roundabouts without a mention of the magic roundabout in Swindon, UK. A big roundabout made up of 5 small roundabouts. https://en.wikipedia.org/wiki/Magic_Roundabout_(Swindon)

I encountered it once and don't ever intend to do so again.

alejohausner• 11 years ago

Roundabouts are unfair. They don't balance traffic loads symmetrically.

Here is what I have observed at one near my house: as you approach the yield line, you can't enter the circle if someone has just entered it on your left. So, if you have lots of cars approaching northbound, and lots of cars approaching westbound, the northbound cars will be on the left of the westbound ones, and will block their entry. You end up with a huge queue on the westbound lane.

This is exactly what happens every day at the evening rush hour (and of course the southbounders block the eastbounders in the morning).

A traffic light would be much better, because its red/green intervals can be tuned to observed traffic tendencies for the time of day.

anotherevan• 11 years ago

I live in Victoria, Australia, and we’ve had roundabouts for ages. I think they are very good for a certain scale of road/traffic. Mostly intersections with moderate amounts of traffic on average, and not high-speed. e.g., the main intersections within housing estates. Having too many of them instead of give-way signs drive you a little batty (I’m looking at you, Warrnambool) while really heavy traffic, major intersections work better with traffic lights.

My daughter recently got her learner license, and she has found roundabouts one of the trickier intersections to navigate. You have to read the traffic flow. This person about to enter on your right is going straight ahead, so will block you entering the roundabout[1], but they have to wait for that person coming the other way from you and going straight through, so you can slip in the gap that creates without cutting anyone else off. As with many things it is familiarity and practice that makes them work[2]. I think roundabouts work very well here for the most part, and my daughter is getting pretty good at reading the traffic. It’s not rocket science[3].

The science of roads and traffic I imagine is a surprisingly nuanced expertise involving a lot of physics and psychology. I find when I cross over the border to New South Wales I feel like a long-tailed cat in a room full of rocking chairs. I eventually figured out it was because the signage was a different distance before the intersection compared to my home state. Once I was aware I could adapt.

[1] We drive on the left side of the road because Australia is in the southern hemisphere.

[2] I bet the first traffic lights caused an uproar. “Why the hell should I stop just because there’s a red light?!”

[3] Oh wait, actually, it is rocket science.

grecy2• 11 years ago

Having too many of them instead of give-way signs drive you a little batty (I’m looking at you, Warrnambool)

My parents just moved to Warrnambool from Mildura. One of their first comments was on the lack of roundabouts :)

Spooky23• 11 years ago

I live in upstate NY, where the DOT is very passionate about installing roundabouts everywhere there is development, as they optimize use of undersized roads, especially in sprawly suburbs. (Search for "Malta, NY" on Google maps and check out the 6 consecutive roundabouts around the I-87 exit)

The problem is they are a cyclist/pedestrian death machine, and the bigger ones cause lots of small accidents. Looking out my office window, I've personally seem a strategically placed streetlight get plowed over about 8 times due to some of the engineering defects of this particular roundabout.

The roundabout in China pictured in the article included an elevated pedestrian walkway -- a feature nearly completely absent in US implementations.

grecy2• 11 years ago

I grew up in Australia in a town nicknamed "The city of roundabouts", I know a thing or two about them.

Upon moving to North America, it was shocking to encounter my first 4 way stop. To this day I still shake my head every time I encounter one. They are non-existent in Australia.

It's been amusing watching the resistance of North Americas to roundabouts, I think, because they are never taught how to use them. Sometimes I ask people the correct way to signal in a roundabout, and I swear I've never had two people in the same room agree.

The city of Calgary installed one, and it was taken out soon after because of a public outcry. In another city in North America I lived in, they put one in, and a lady promptly drove straight through it, crashing her car. She sued the city and one, because it wasn't fair to go and put in a roundabout like that.

slavik81• 11 years ago

There's a bunch of roundabouts in Calgary, though admittedly they're not common.

nl2• 11 years ago

There's two types of round-abouts: the Continental European kind and the UK/Australian kind. The UK/Australian kind are designed to keep traffic moving, so the angles are arranged to make entering similar to a merge. European ones are designed to slow traffic, so you enter at a right angle and have to turn hard to enter.

The UK/Australian kind kill cyclists[1]. I understand the European kind are safer, but I don't have personal experience with them (OTOH, I have been hit at a roundabout, and seen another 2 car/cyclist accidents).

[1] http://acrs.org.au/files/arsrpe/Cumming%20-%20High%20rate%20...

[2] http://search.informit.com.au/documentSummary;dn=38012654206...

empressplay• 11 years ago

Roundabouts don't kill cyclists, unobservant drivers kill cyclists. They kill cyclists on the straight and at intersections too. Don't blame the roundabout for it.

nl2• 11 years ago

That's correct of course. However, roundabouts increase the risk enormously. I assume you read the stats in my links?

49% of crashes at roundabouts involved cyclists

It specifically addresses the "look but didn't see" problem, and how the Australian design makes that worse: Herslund & Jørgensen videoed cars and cyclists at roundabouts and noted that bicycles are often located in drivers’ peripheral vision. They suggest that experienced drivers use fast search strategies such as concentrating on where cars usually are, so may be more prone to LBFTS collisions than less experienced drivers.

h1fra• 11 years ago

The case of France is a quite simple. Governement wanted to lessen road related death, so they actually subventionned city and state to build roundabouts.

They are flourishing everywhere, but at this point there is not much need for it anymore. But they keep building them to keep their subventions, it redistribute money to local company (and also keep mayor in their place).

Sometimes you can drive 100Km without encoutering a single crossroad but hundred of useless roundabouts, it actually reduce speed on main road and provide little but no value to actual cross section.

sparkie2• 11 years ago

Half* of the UK's roundabouts are in Skelmersdale, and they provide little function because there are so few cars on the road in the area. They probably increase emissions because you've got to drive that much further to get where you want (The largest of these roundabouts is half a mile in circumference) - and with nothing but grass, woodland and strange "art" sculptures in the middle, they're a huge waste of land.

*Approximation

JoeAltmaier3• 11 years ago

The most curious definition of 'waste of land' I've encountered in a while. Are national parks also a waste? How about wildlife refuges? Oh! Scotland! That may also qualify.

JoeAltmaier3• 11 years ago

If they replace a stop sign, then they're strictly better in terms of fuel economy, right?

dsfyu404ed• 11 years ago

A large problem with roundabouts is that municipalities tend to build them as poorly or put them places where a light should be.

filling the center with landscaping that obstructs view
putting them where a computer controlled light should be (small road meeting large road, stays green toward large road the vast majority of the time)
put them where a flashing yellow/red should be (tiny road crossing main road
putting roundabouts in areas that see a large volume of heavy trucks

Roundabouts don't work very well on roads with highly differing traffic volumes

The Case for More Traffic Roundabouts

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