In the USA the number of roundabouts has doubled in the last decade. They are pulling out stop signs and installing roundabouts in cities; New York just got its first and Vancouver is full of them in residential areas. Jeff Shaw of the Federal Highways Agency tells the Guardian that they are safer.
"Most of the time, roundabouts are a very competitive alternative to other forms of intersection, from both an operational and safety standpoint,” says Shaw. He cites research suggesting that severe crashes – those that result in injury or loss of life, through T-bones caused by cars running red lights – are reduced by 80% when you replace intersections by roundabouts. “The slower speed and angle at which cars approach roundabouts has a profound impact on the severity of any collision that might occur,”
Perhaps this is true for cars. In the Province of Ontario where I live, they are putting a lot of them in, claiming they are safer, have higher capacity, fewer stops, less idling and air pollution and lower maintenance costs.
But in Britain, according to Ian Wylie in the Guardian, many are being torn out and replaced with (gasp) traffic lights. One of the reasons is that they are great for cars but not so terrific for pedestrians and cyclists.
Cyclists have a demonstrably harder time with roundabouts. Research suggests that on large urban roundabouts, cyclist have an injury rate 10-15 times that of motorists. There is a tendency for motorists at roundabouts to look through cyclists while watching for other motor vehicles, hence the frequency of “SMIDSY” (Sorry, mate, I didn’t see you) collisions. And even collisions at slower speeds can be fatal for cyclists.
And indeed, the high-profile death of Moira Gemmill, "a major figure in the London architecture and design scene," happened on a roundabout.
I recently was riding in Vancouver and never knew quite what to do with the roundabouts. Many of the cyclists I was with on a big tour just turned left without properly going right around the island; many cars went so fast that I stopped and let them go even though I had right of way, they are bigger and heavier than I am. One Vancouver critic of traffic circles writes that "many people, motorists and cyclists included, not know the proper way to use them, but they can also be very dangerous in icy or wet weather."
On the other hand, coming from a city with four way stops at almost every intersection, it was perfectly clear that cars and bikes moved more smoothly, and they were not all breaking the law with rolling stops in cars or Idaho stops for bikes. After a couple of hours of getting comfortable with them, I began to really appreciate how much better it was than the four way stop, how I could keep moving, how there were rules that worked for both cars and bikes.
In Britain, where of course there is a UK Roundabout Appreciation Society, they claim that " roundabouts promote the virtues of compromise and cooperation. They allow drivers to make their own decisions and assess others’ actions." I think this is probably true, and hope that the trend in the UK to tear them out doesn't come to North America too.