After years of study, the Virginia highway department is embarking on a $9.2 million project to eliminate one of Arlington's major traffic bottlenecks, the narrow four-lane stretch of Arlington Boulevard (Rte. 50) between Glen Carlin Road and Four Mile Run.

Jay D. Lawson, an inspector for the Virginia Department of Highways and Transportation, said the state plans to begin widening Rte. 50 from four to six lanes between Grenada and Manchester streets next summer. The highway, a major commuter artery between central Fairfax County and downtown Washington, is used daily by 49,000 cars. The widening will take three years to complete.

The road already is six lanes elsewhere in Arlington, and state and county transportation officials say the narrow section is a traffic hazard and breaks the flow of the car-pool and bus traffic that uses the third lane during rush hours.

"It'll eliminate a lot of accidents, a lot of safety hazards," Lawson said of the project.

The Arlington County Board is expected to endorse the project Aug. 13.

William Scruggs, head of the county's traffic engineering division, said 28 accidents were reported last year on that stretch of Rte. 50, which is a little more than a half mile.

The project also will entail replacing two badly deteriorating bridges and widening Carlin Springs Road from South Second Street to North Jefferson Street from two to four lanes. Nine accidents were reported on that section of road last year.

John Hummel, chief of the county's engineering division, said the bridge over Carlin Springs Road is so structurally deficient that it got only four out of 100 points when it was rated for the state last year, making it one of the five worst bridges in Northern Virginia.

The Four Mile Run bridge, near Grenada Street, also is considered one of Arlington's worst bridges structurally, Hummel said.

While both bridges are safe to drive on, Hummel said, the bridge over Carlin Springs Road is so low that trucks frequently ram into it and get stuck. The state plans to raise the bridges over Carlin Springs Road and Four Mile Run.

"We can't wait for it to be done," said Sandy Keyes, president of the Glencarlyn Citizens Association. "Everybody wants to see that bridge over Carlin Springs Road repaired, and the widening of the road is generally looked at favorably because of the backup there now. We think it will mean increased safety, and everyone is looking forward to that."

But the association does not find the planned project flawless, Keyes added. Residents are concerned that a higher bridge over Carlin Springs Road will increase truck traffic through their neighborhood, and the road will become a convenient connector to the Rosslyn-Ballston Metrorail corridor.

"We want a new bridge, but not the truck traffic," Keyes said.

They also are unhappy with plans to change a two-way service road that runs along the south side of Rte. 50 to a one-way eastbound service road near the southwestern corner of Rte. 50 and Carlin Springs Road. They contend it will create safety hazards and further fragment the community.

Residents along South First and South Second streets at South Madison Street often use the service road to get to the other side of Carlin Springs Road for shopping and neighborhood functions. To return home, they would have to enter westbound Rte. 50, cross two lanes of high-speed traffic in a very short distance and turn left on Manchester Street, which the county's traffic department declared the ninth worst intersection in Arlington last year.

The community already is fragmented by the location of Kenmore Intermediate School in the midst of it, Keyes said, and restricting the two-way service road to one way only would intensify the problem.