Laburnum/Hermitage roundabout detailed in TD

The idea is to slow traffic and reduce accidents at the intersection of two major arteries, said Gary DuVal, deputy director of public works.

“There are a lot fewer conflict points,” he said “Everybody is going right and you’re not turning against traffic.”

DuVal said a growing number of traffic engineers believe it would be safer to let traffic flow constantly through the intersection using a roundabout than it now is to rely on red and green traffic lights to keep drivers from slamming into each other.

A 1998 study through the federal government’s National Cooperative Highway Research Program found a 37 percent reduction in accidents and a 51 percent reduction in injuries when roundabouts replace traffic lights.

Roundabouts aren’t like the traffic circles that are the source of so many Washington driving nightmares — even though there is a circle at the center of both types of intersection.

The difference is in the roads leading up to the circle. In the approaches to a roundabout, there typically are small triangular concrete islands that narrow the lanes and guide vehicles into the central circle.

“It lets drivers smoothly merge,” DuVal said. “It’s designed for people to travel through at about 23 mph, and you’re looking left and easily merging with other traffic going 23 mph.”

…by narrowing traffic lanes, “we’re going to be taking quite a bit of asphalt out,” he said. There will be more green space around the base of the monument.

In addition, the plan calls for reshaping the medians on Laburnum and Hermitage, so that they will curve. The city would move pedestrian crossings away from the intersection, which DuVal said should make it safer to get across the busy streets at the intersection that is also home to Linwood Holton Elementary School.