Citadel Study on Roundabouts to Help Guide Future Development

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As populations surge and traffic concerns grow, transportation engineers are becoming increasingly interested in how roundabouts can keep traffic moving and cut down on accidents.

Dimitra Michalaka, assistant professor in the Department of Civil and Environmental Engineering at The Citadel, has been researching select roundabouts in Beaufort, Berkeley, Horry and Charleston counties. Over the last three years, Michalaka and six students from The Citadel have looked at 49 roundabouts (collecting data on 12 of them) to determine access management as well as their impact on pedestrians and cyclists.

Roundabouts, because they keep vehicles moving in a circular motion, don't require left turns so they are safer and cut down on collisions. Drivers also have to reduce their speed going through a roundabout, so if there is a collision, the impact is less forceful. Roundabouts keep traffic flowing, making them more efficient than a four-way stop.

More and more states are encouraging the use of roundabouts, which are quite popular in Europe and widely used in a few select states like Wisconsin and Florida. In her research Michalaka found the number of roundabouts in the United States has grown from just a handful a decade ago to more than 2,000.

States are looking more closely at roundabouts because they are often less costly to install than an intersection with a traffic signal, tend to be safer, and usually have lower operations and maintenance costs.

Michalaka is still studying the best way to install roundabouts in areas with a high number of pedestrians and cyclists. A big question is if there's not a signal for pedestrians and they simply have the right of way, what happens if vehicles are stopped for a period of time and can't move? She'll continue that research for another year.

This study will be used to help determine the best locations for roundabouts versus other types of intersections, Michalaka says. Plus, her research will help provide guidance on how to let pedestrians best navigate the multiple crossings of a roundabout.

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