The N.H. Department of Transportation (NHDOT) is making an effort to build roundabouts at certain intersections across the state. Click here to learn more.
There is a difference between a roundabout and a rotary or traffic circle.
A rotary/traffic circle is a type of intersection that directs both turning and through traffic onto a one-way circular roadway. Rotaries typically feature high speeds inside the circle and on the approaches and exits.
A roundabout is also a one-way circular roadway with approaches and exits, but its diameter is tighter than a traffic circle, forcing motorists to navigate the road at a slower speed.
NHDOT is using the roundabout concept to replace intersections that had been controlled by traffic signals. Roundabouts are also being used to replace traffic circles, which occurred in Lee in 2015 at the confluence of routes 4 and 125.
New Hampshire, according to transportation officials, has 40 roundabouts and the number is growing. A roundabout, for instance, will be built in Dover to replace the traffic signals at the intersection of Route 4 with Spur Road and Boston Harbor Road, near the entrance to the Spaulding Turnpike (Route 16).
Traffic engineers say traffic circles, because of the higher speeds, are dangerous because of the chance of high-speed accidents that risk injury and death. They also argue that certain signaled intersections are equally dangerous because of the risks of serious rear-end collisions.
Roundabout proponents say they have a more calming effect on motorists, maintaining traffic flow through an intersection but at slower speeds, thus reducing accidents that cause injury or high property damage.
Opponents of roundabouts say they can be confusing to motorists, thus creating a greater opportunity for accidents. Their slower nature can also create congestion and stop-and-go traffic, raising the chances of rear-end collisions.
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