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Roundabout Pondered for PV/Braddock Intersection

Anyone who's had to drive through Centreville's Pleasant Valley/Braddock Road intersection at rush hour knows it's anything but fun. So the Virginia Department of Transportation (VDOT) is proposing to install a roundabout there.

"BY TRAFFIC count, it warrants a [signal] light," said Judy Heisinger, transportation chairman for the West Fairfax County Citizens Association (WFCCA) Land-Use Committee. "But there's not any money, and roundabouts are less expensive to build than traffic signals."

Currently, Northern Virginia has no roundabouts, she said, but something needs to be done about this intersection. "I've counted as many as 50 vehicles waiting at the four-way stop [there] to go west on Braddock at night and east on Braddock in the morning."

On July 14, VDOT Area Engineer Laura Hegler gave a presentation on roundabouts to the Virginia Run executive board and, said Heisinger, the board liked what it heard. So she arranged for Hegler to do the same thing at the Aug. 16 WFCCA meeting.

With a roundabout, said Hegler, there'd be no left turns at that intersection. Instead, every vehicle would turn right to enter the circle. "Coming from Virginia Run on Pleasant Valley Road, you'd approach a triangular island that would slow traffic down," she explained. "And there'd be a raised circle in the middle of the island, about 100 feet in diameter — just large enough for school buses and cars."

She said the main benefit of roundabouts is that they lower the traveling speed. This one would be designed for 10-15 mph. "Everyone yields to whoever's in the roundabound, like a one-way roadway," said Hegler. "Once traffic passes and you can get in there safely to the right, you do. It's like turning right on a red light. It's called 'yield at entry,' and it keeps traffic from locking up and allows free flow of the cars."

Heisinger said it would be a savings in operating cost and land mass otherwise needed for turning lanes. "And with people going slowly, if there were fender-benders, there wouldn't be as many fatalities," she said. "[WFCCA has] reservations about it, but we're willing to hear the presentation."

Hegler — who lives in Centreville and is familiar with that intersection — said several local residents have sent requests to VDOT, asking for a traffic study or signal there because of the delay, both ways, especially during the morning and evening rush hours. They also noted their difficulty getting through there at 3 p.m. to pick up children from school.

SHE SAID the last time VDOT conducted a 12-hour, turning-movement count there — examining how many vehicles went through that intersection and which way they were turning — was July 16, 2003. So it plans to do a new traffic study there in the fall.

Although the traffic volume there merits a signal, said Hegler, "Due to the geometry of the intersection, there's a tight turning-radius and we couldn't have concurrent left turns from either approach because there's just no room. Right now, it's hard for school buses to turn left from either road."

So in order to install a traffic signal there, she said, "We'd have to stretch out the intersection by moving back the stop bars and add turns on both roads." Because of this problem, VDOT analyzed three possible scenarios to solve it.

One was to add a signal with no turn lanes. But, said Hegler, "You'd have to have a four-phase signal, with each phase occurring one at a time, and it would end up increasing the delay." Another idea was to add 100-foot, left-turn bays for all approaches, each allowing five cars to stack up there.

"But the queues would be pretty significant, would spill back into the through lanes, and opening that intersection further could lead to more significant crashes," said Hegler. "Right now, there's a stop-sign control and no one's going fast."

The third scenario was the roundabout. "This would be safer than people blowing through the stop sign or through a signal because they'd have to slow down for this," said Hegler. "It would force them to negotiate a physical object. Roundabouts have been shown to reduce fatalities and injury-accidents by as much as 70 percent."

She said they may even cost less to maintain than a signal because the cost of electricity for a large intersection could be as much as $5,000 a year. In addition, roundabouts increase an intersection's capacity, but decrease the delay.

"With an intersection with a large volume of left turns — especially from Pleasant Valley Road to Braddock — you'd have to add an extra-long turn phase for left turns," said Hegler. "But that would increase the delay for everything else."

She said roundabouts can generally handle 1,800 vehicles per hour. And according to VDOT's 2003 traffic count, some 1,300 vehicles per hour passed through the Pleasant Valley/Braddock intersection. Said Hegler: "There are probably more now, but I think a roundabout would be able to handle them."

VDOT'S PLANNING to do its new traffic count in the fall when school is in session and residents are back from vacation, so it can get a better picture of the traffic volume there under normal conditions.

Hegler said roundabouts shouldn't pose any problems to people on bicycles "because you only have to worry about what's turning right against you. And we can design a pedestrian-refuge area in the middle of the channelized island."

She said a roundabout is VDOT's preferred alternative there because of safety and capacity. "An intersection such as Braddock Road/Pleasant Valley is a perfect fit [for one] because the traffic volumes are right," she explained. "You've got a small amount of space and there's a large amount of traffic turning left. So it makes sense here."

Meanwhile, Supervisor Michael R. Frey (R-Sully) is keeping an open mind and waiting to hear what local residents think of the idea. "That intersection certainly needs something, and traffic lights are not the answer to everything," he said. "And there's no question that the land required for a traffic light there would be more than is needed for a roundabout."

Actually, said Frey, "My initial reaction was, 'I don't think so.' But I met with VDOT twice, in the past month-and-a-half, and now I've come to the position that, if there's some degree of community support, I'm willing to try it."

He said a roundabout didn't become a possibility there until a month ago when VDOT got some federal funds for it. And, he stressed, VDOT still has to put together a design and figure out and acquire the necessary right-of-way.

"Cox Farms owns one corner there, and the [county] Park Authority owns the other three corners," said Frey. He also noted that a community meeting would have to be held.

"When I first moved here in 1975, I went to AU [American University] in the District, and I hated the roundabout there," he said. "It had too many lanes and too many people coming into it. But I found out, not all circles are the same [and the one at Pleasant Valley/Braddock Road would be much simpler]."

Nonetheless, said Frey, "You're still facing people's perceptions. And some people say they couldn't get out of their homes along Braddock Road if there were no breaks in the traffic. But the objective is to move traffic through a heavily congested intersection."

So, he said, "a lot of outreach" would need to be done before local residents are sold on this somewhat unusual idea. "The Virginia Run board said, 'Let's give it a shot,' and I think others may, too," said Frey. "Then the [Board of] Supervisors would probably have to approve the design concept and weigh in on the matter."