Roundabouts

Traffic circles have been part of the transportation system in the United States since at least 1905 when one of the first circles was built in New York City. Subsequently, many large circles or rotaries were built in the United States. The prevailing designs enabled high-speed merging and weaving of vehicles. Priority was given to entering vehicles, facilitating high-speed entries. High numbers of crashes and congestion in the circles led to rotaries falling out of favor in America after the mid-1950s.

The modern roundabout was developed in the United Kingdom to rectify problems associated with these traffic circles. In 1966, the United Kingdom adopted a rule that required traffic entering circling intersections to yield to circulating traffic. This rule prevented circular intersections from locking up by not allowing vehicles to enter the intersection until there were sufficient gaps in circulating traffic. In addition, smaller circular intersection designs slowed vehicle entry and circulating speeds. These changes significantly improved the safety characteristics of roundabouts by reducing the number and the severity of crashes.

There are an estimated 300,000 signalized intersections in the United States, according to the Federal Highway Administration. About one-third of all intersection fatalities occur at these locations, resulting in roughly 2,300 people killed each year. Furthermore, about 700 people are killed annually in red-light running collisions.

Roundabouts have demonstrated substantial safety and operational benefits compared to most other intersection forms and controls, with especially significant reductions in fatal and injury crashes. Because the only movement allowed upon entry or exit from a roundabout is a right turn, the occurrence of crashes that result in injury is substantially reduced. Small-angle collisions, the type of collisions that can occur as a result of a right-hand turn, are typically less severe than other types of collisions.

Approach:

• Slow down and stay in your lane
• Yield to vehicles already in the roundabout
• Obey one-way signs at all times
• Yield to pedestrians and bicycles if there is a crosswalk

Enter:

• Merge with traffic in the roundabout, yield if necessary. Traffic already in the roundabout has the right of way.

Proceed:

• Continue through the roundabout until you reach your exit point. Avoid stopping in the roundabout

Exit:

• Signal and exit to the right
• Left turns are completed by circling around the center island and then making a right turn to exit

Roundabouts can easily accommodate emergency and large-sized vehicles. Drivers should behave in the same manner as they would on any other road if an emergency vehicle approaches: carefully move as far right as possible and, if necessary, stop until the emergency vehicle passes.