IN DEEPEST Washington state, trooper Dusty Pierpont stands in front of a roundabout trying to persuade motorists to like them. Washington started building roundabouts in 1997. By 2001 there were 17; now there are over 100, according to Brian Walsh of the state's transport department. But trooper Pierpont is still needed to soothe those first-time (or even tenth-time) nerves.

America may be sluggardly on general road-building, but it is experiencing a boom in modern roundabouts, which (for those who have not yet met them) do the job of any ordinary four-way, stop-sign or traffic-light crossroads. They are more efficient and safer than the old traffic circles, such as Columbus Circle in Manhattan, which have been built in America for the past century. (Modern designs include mechanisms for slowing traffic down as it nears the roundabouts, for example, and do not allow pedestrians onto the centre of the circle).

Although exact statistics are hard to come by, the Insurance Institute for Highway Safety (IIHS) estimates that America has 1,000 modern-style roundabouts. Britain has 10,000, Australia 15,000 and France 20,000. Nowadays America is adding perhaps 150 to 250 new roundabouts a year, not counting mini-ones in suburbs. Even the Alaskan town of North Pole is building three new roundabouts, one at the corner of Santa Claus Lane and St Nicholas Drive.

The arguments for roundabouts are strong. There are no costly traffic lights to build or maintain. Unless something is coming round, cars need not stop, so congestion is reduced and fuel is saved. Most important is safety. About 45% of all crashes in America occur at crossroads, often because of misjudged left turns. At a roundabout, outside Britain and other countries that drive on the left, drivers can only turn right. A 2001 study by the IIHS found that roundabouts have 80% fewer crashes with injuries than ordinary intersections. Other research also points to big reductions.

So roundabouts may be a small reason why America's roads are slowly getting safer. Last year injuries in motor-vehicle crashes were down an estimated 6%. Even so, drivers are often sceptical. “We lose far more roundabouts that could have been built, because of city councils or a trucking company,” says Mr Walsh. There are also plenty of doubts in North Pole, according to the Fairbanks Daily News-Miner. After all, who wants Rudolph prancing round in circles?