Traffic Circles and Safety

As promised in the last post, here’s one on traffic circles, a subject that I have also taken up here. From The Economist:

One of their main attractions, says Mayor Brainard, is safety. The Insurance Institute for Highway Safety, an independent research group, estimates that converting intersections with traffic lights to roundabouts reduces all crashes by 37% and crashes that involve an injury by 75%. At traffic lights the most common accidents are faster, right-angled collisions. These crashes are eliminated with roundabouts because vehicles travel more slowly and in the same direction. The most common accident is a sideswipe, generally no more than a cosmetic annoyance.

What locals like, though, is that it is on average far quicker to traverse a series of roundabouts than a similar number of stop lights. Indeed, one national study of ten intersections that could have been turned into roundabouts found that vehicle delays would have been reduced by 62-74% (nationally saving 325,000 hours of motorists’ time annually). Moreover, because fewer vehicles had to wait for traffic lights, 235,000 gallons of fuel could have been saved.

While I’m a bit skeptical of the time and fuel savings estimates there at the end, I do agree with the overall safety and convenience of traffic circles instead of lights. Here in the Triangle they are becoming more and more common. I have to admit that sometimes people do seem very confused by them, trying to turn left instead of going around and so on. However, this is because most driver education programs in the United States don’t educate people about traffic circles, a problem that should be relatively easy to overcome. I’d be interested to hear from people who have spent time driving in countries with lots of traffic circles as to whether or not they agree with the claims of safety or convenience.

7 thoughts on “Traffic Circles and Safety

  1. I’m just going to toss in my tuppence here since I have lived in two cities that share borders with the Mayor Brainard mentioned in the article cited.

    Roundabouts of the type built here (there are a few different kinds) have been excellent additions. He’s built them all over Carmel and they have even spread to intersections outside of his jurisdiction due to their obvious improvements (primarily in resolving congestion). Hamilton Co, where Carmel, Indiana is, is one of the nations fastest growing counties. It butts up against Marion Co, i.e., Indianapolis, the 12 or 13 largest city in the country. Most of Hamilton Co’s growth is in its two southern most cities (Fishers and Carmel, both on the border between Marion and Hamilton Co) But fast growth in Hamilton Co and on Indianapolis’ northside is hampered by the inability to make the kinds of infrastructural developments needed to support that many more people. That is, these areas are already “developed,” so widening roads is time consuming, expensive, and very likely to upset the voters whose property you diminish either by taking it outright or by getting rid of sidewalks and easements. But changing an intersection from…well…an intersection…to a roundabout is something than can easily be accomplished while improving the volume capacity of the existing roads. Opinions locally (I still live in Indianapolis, just further south) are obviously varied, but the consensus seems to be positive. They’re annoying going in…And a few years ago when they first appeared there was a small learning curve. But now people are accustomed to using them and traffic moves very smoothly. It’ll be a few years before we see good data on accidents but I anticipate good results from those studies.

  2. Unfortunately, people in the US are just as confused by the rules of stoplights and stop signs. I’ve seen people wait three cycles at an unprotected left turn because they don’t know they are supposed to pull out into the intersection and go when the light turns red if an earlier opportunity does not present itself. We might as well switch to traffic circles because it’ll just be the same people getting confused, anyway, while saving the rest of us some time.

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