Roundabout eases traffic congestion
September 23, 2011
The Directorate of Public Works hopes the traffic roundabout in front of Fort Belvoir Community Hospital leads to efficient maintenance and traffic flow.
The roundabout, which was completed in July, connects Pence Gate, FBCH, the Community Center and Belvoir Road.
Chris Landgraf, chief facility planning master planner for the Directorate of Public Works, said the roundabout has a 70 foot diameter and is designed to handle any type of vehicles, though he hasn't seen a tractor trailer navigate the intersection.
The roundabout also is open to bicyclist and has crosswalks for pedestrians.
"We were trying the get the biggest bang for the buck here, in the sense of moving the traffic through pence gate with little or no delay," Landgraf said.
Landgraf said the intersection, which is anticipated to handle 2,000 vehicles trips daily, was constructed because DPW believes it was the best alternative to directing the increased traffic heading to FBCH via Pence Gate on Belvoir Road.
DPW believed a traditional intersection could have potentially slowed down traffic on Route 1 because of the frequent stopping associated with traffic signals.
According to Virginia Department of Transportation's website, roundabouts are the safest at-grade intersection.
The circular intersection causes a 90 percent reduction in fatal crashes, a 75 percent reduction in injury crashes, a 30 to 40 percent reduction in pedestrian crashes and a 10 percent reduction bicycle crashes.
The reasons behind these reductions are the speeds and angles at which motorist drive. The typical roundabout in Virginia is 25 mph or lower. This gives drivers more time to react to each other vehicles and pedestrians. The circular dimensions of the roundabout also minimize the chances of severe crash collisions.
Landgraf said the open visual space of a roundabout area also gives drivers ample time to make good decisions.
"The reality is that you can pretty much go undeterred if you're paying attention," Landgraf said.
He theorized that Belvoir's roundabout should be more cost effective as well.
The installation won't have to spend money on repairing poles and light bulbs for traffic signals.
There will be cost for landscaping around the area, "but for long term maintenance and upkeep a roundabout should cost less than a four way intersection," Landgraf said.
Entering a roundabout, traffic must yield to vehicles already in the intersection.
Landgraf said motorist entering the roundabout should drive straight through on an east west or north south path to remain on the outside lane. Motorists who are making a turn of direction should drive in the inner lane and exit the circle when at the appropriate turn.
"I think if people approach the roundabout with caution and yield as they're supposed to," Landgraf said, "then I don't think we'll have any problems with this roundabout."
As of now there will be only one roundabout on the installation.
Landgraf said the development of any additional rotary systems would depend on space and constraints.
Belvoir's numerous hills and offices located close to intersections on the installation road grid limits where DPW could potentially place another roundabout.
Natural restrictions such as Belvoir's Forrest and Wild Life Corridor further limit options.
Public reception and maintenance cost will also have an impact on future development as well.
DPW will also have discussions about constructing a sidewalk that will lead from Pence Gate through the roundabout and into FBCH to accommodate the pedestrians entering the gate via bus drop-off.