Intersections

The concept of a round intersection dates back to at least 1903. It was 1903 when Eugéne Hènard suggested a "gyratory" operation for traffic control at intersecting streets. It sounded like a good idea to the French and they adopted it at Place de l Étoile now Place Ch. d Gaulle. In the USA the earliest we used a "gyratory" intersection or traffic circle was 1905 when Columbus Circle was installed by William Phelps Eno in New York City.

According to a book called The Design of Roundabouts by Mike Brown, the trend to use the word roundabouts was formally recognized in the mid–1920s in Great Britain in a joint effort between the Ministry of Transport and the Town Planning Institute. Notable here because this may be one place where modern roundabouts get confused.

Early circular intersection designs gave priority to entering vehicles facilitating high speed entry, high crash experience and congestion. When the early gyratory systems or traffic circles were used in the USA there was substantial trouble regulating traffic. Local ordinances were not enforceable and there were not any uniform rules of the road in the United States so the traffic circle fell out of favor by the 1950s.

In the past four decades, modern roundabouts or circular intersections have been used in Europe and Australia. Despite the tens of thousands of modern roundabouts in operation around the world, roundabouts have been slow to gain support in the USA. This lack of support is probably because of the bad experience motorists had with traffic circles or rotaries that were built in the early half of the twentieth century. Severe safety and operational problems caused traffic circles, (rotaries or gyratories) to fall out of favor with motorists and engineers by the 1950s.  Think about how designs of cars, and stereo equipment and computers and telephones have changed over the past twenty years. The design for moving traffic through intersections in a counter clockwise circular manner has changed too. 

Modern roundabouts give vehicles in the roundabout (in the circular roadway) the right–of–way. This was a national change that started in England in 1960s with a yield at entry rule. The motorists entering the roundabout yield to the traffic in the roundabout.

The modern roundabout arrived in the USA in 1990 in Summerlin, a subdivision in Las Vegas. The first roundabout freeway interchange, designed by Leif Ourston was built in 1995 at the I-70 interchange in Vail Colorado. Avon, Colorado, the next I-70 interchange after Vail, in 1998 built five roundabouts between the I-70 interchange and the Beaver Creek Mountain Ski Resort. Several other roundabouts have been built in just about every state in the USA since that time. Just because every state has one or several does not mean that everyone knows how to use them. Thanks for reading about roundabout history. Read on for more and be sure to check out the roundabout rules of the road.

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