Fairfax County supervisors on Oct. 19 were slated to give the go-ahead for a project-administration agreement with the Virginia Department of Transportation (VDOT) to replace a deteriorating single-lane bridge with a two-lane span on Hunter Mill Road over Colvin Run.
The current bridge, located between the Vienna and Reston areas, is “structurally deficient and must be replaced immediately,” county staff said. Officials last year noted significant corrosion of the span’s steel girder webs and flanges.
In order to remain open to traffic, the bridge on Feb. 29, 2020, received emergency reinforcement via additional wooden beams beneath its I-beams, saw its load rating decreased to 10 tons and its lane width shortened to 10 feet. The bridge also had received additional timber shoring underneath in 2012 and had knee braces added in 2016.
The new two-lane bridge, which will cost about $5 million, will have the same number of travel lanes as the rest of Hunter Mill Road.
While most of the project’s cost will be covered by VDOT “State of Good Repair” funds, Fairfax County will chip in $408,000 for several pedestrian improvements at the bridge. These upgrades will include a median refuge, rectangular rapid-flashing beacon and a splitter island that will divide approaching lanes and encourage motorists to slow down.
The improvements are designed to bolster safety and accessibility for drivers, pedestrians and bicyclists where the roadway meets Colvin Run Stream Valley Trail slightly south of the bridge. In addition, the new bridge will be designed to permit a future trail crossing over Colvin Run.
County supervisors last December endorsed VDOT’s concept for a 40-foot-long replacement bridge with two 11-foot-wide travel lanes to replace the existing 30-foot-long one-lane span. The current bridge was built in 1974 and handles about 8,500 vehicles per day, VDOT officials told the county last year.