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Tuesday, June 6, 2017

Mini-roundabout would improve traffic flow on Ravensworth Road

Ravensworth Road at Jayhawk Street.
A temporary mini-roundabout to be installed this summer at the intersection of Ravensworth Road and Jayhawk Street/Fountainhead Drive in Annandale is supposed to improve traffic flow and pedestrian safety and deter speeding.

After learning about the roundabout project at a meeting June 5, most residents seemed to think it might work, although a couple of skeptics said they preferred a traffic light.
An illustration of the roundabout.
“Big traffic circles don’t work well; this is very different,” said Wei Zhang, a program manager with the Federal Highway Administration (FHWA) Office of Safety Research and Development.

Mason Supervisor Penny Gross acknowledged she had some doubts about the roundabout when she first heard about it, but has seen the concept work well in other jurisdictions.

Gross said the project “is deserving of a tryout,” because it could be removed if it isn’t successful. The roundabout will stay in place for 12 to 18 months, so it could be evaluated during several seasons.

Cost is also a factor, she said. A traffic signal would cost $300,000 to $400,000, while the temporary mini-roundabout would cost $175,000, with the funds coming from the FHWA, not the county, although the Virginia Department of Transportation will be responsible for maintenance.

Cars would slow down, to about 15 to 20 mph, as they approach the roundabout, Zhang said. As they enter the roundabout, they would yield to traffic already in it.

A roundabout would have higher capacity than a regular intersection with a traffic light or stop signs, he said. That’s because four vehicles would be able to enter at the same time, and would all go in the same counterclockwise direction. As a result, cars won’t be piling up as they wait to get through the intersection.

A mini-roundabout at N. Irving Street and 1st Place N. in Arlington. 
Median strips would be installed, giving pedestrians a refuge as they cross the street, which would also increase safety. Existing bike lanes would stay in place.

Zhang showed videos of similar roundabouts in other parts of the country where pedestrians had an easier time crossing intersections, and large trucks and emergency vehicles did not have problems negotiating roundabouts. Commercial trucks are already banned on Ravensworth Road.

Several people at the meeting said the main problem on Ravensworth is high traffic volume. A traffic analysis found 50,000 cars pass through that intersection every day. “This will not reduce volume but it will slow traffic and keep it moving,” Gross said.

A couple of people spoke about how difficult it is to make left turns onto Ravensworth from side streets or townhouse parking lots. The roundabout would solve that problem because drivers could turn right onto Ravensworth, then use the roundabout to make a legal U-turn.

The raised circle in the middle of the roundabout would be made of a durable material like that used in railroad ties. It would be screwed into the road and would take only one or two days to install. 

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