Research says driving in circles a sensible congestion solution

By John Henderson | 978-7277
Published: June 26, 2008

Even as Charlottesville’s City Council recently opted against using a roundabout design for the Meadowcreek Parkway interchange, new traffic safety research by a Greene County organization indicates that roundabouts are a safer and more fuel-efficient alternative to traditional stop-and-go intersections.

The Insurance Institute for Highway Safety’s June report goes on to identify several ways to reduce the number of accidents that happen in roundabouts. IIHS, a nonprofit research organization funded by auto insurance companies, conducts crash tests in its Ruckersville facility and researches ways to improve road safety.

Roundabouts are much safer than traditional intersections, the institute previously reported in 2000, but with clearer markings, more signs and easier transitions, roundabout safety could be improved.

Most of the accidents that happen in roundabouts are minor, the latest report states. In a study involving 38 roundabouts in Maryland, the institute found that three-quarters of the accidents caused only property damage and none was fatal. Bicyclists and pedestrians accounted for six of 283 total crashes.

Some drivers object to roundabouts as being confusing and potentially dangerous, the report states, but an earlier IIHS study suggests that the number of accidents in roundabouts is significantly lower than in traditional intersections.

Where roundabouts have been installed, crashes have declined by about 40 percent and injury-producing crashes have declined by about 80 percent, the institute reported. The central island around which traffic flows keeps speeds between 15 and 20 mph in urban areas, greatly reducing the possibility of a high-speed collision.

The most common accidents involve cars running off the road, colliding with other cars as they merge, rear-ending and sideswiping. The institute recommended longer curves into the circle, better lighting and pavement markings, and landscaping around the central island.

Roundabouts also reduce gas consumption and improve transit times by keeping cars moving instead of idling at traffic lights, a 2005 IIHS study showed. If roundabouts were built at 10 sites in Northern Virginia, the total fuel savings would be 235,000 gallons a year and delays would drop by 62 percent to 74 percent, the institute reported.

A steering committee recently recommended several designs with roundabouts for the construction of a new interchange at the U.S. 250 Bypass and McIntire Road. Charlottesville’s City Council, however, decided at a June 4 work session to use a diamond interchange that will take up less space.

At least five roundabouts have been built in Albemarle County, according to Juandiego Wade, the county’s senior transportation planner. Wade said that the Virginia Department of Transportation and local planners are increasingly using roundabouts in lieu of stoplight intersections to reduce traffic and heighten safety, but currently there are no roundabouts in planning or construction in the county.There are more than 1,000 roundabouts in the United States. By comparison, French engineers build more than 1,500 a year, the institute reported in 2001. But the popularity and use of roundabouts in the U.S. is growing, said Russ Rader, IIHS director of media relations.

“Roundabouts are definitely catching on in the U.S. as people see the results, both in terms of safety and also now with concerns over fuel consumption,” he said.