Burleigh Construction Co. Inc. recently began a bridge replacement project on Route 615 for the Virginia Department of Transportation (VDOT).
Burleigh, the prime contractor, will be installing a precast concrete structure in place of a timber deck structure, which are becoming less common in the state. The bridge spans Deep Run Creek on Route 615 at the Stafford and Fauquier County line in Virginia.
The Concord, VA-based contractor started site preparation work for the $312,000 contract Jan. 9. After some minor clearing and grubbing, the contractor will replace the existing two-span, timber deck structure with a single-span, precast concrete three-sided structure. The bridge measures roughly 34 ft. (10 m) long and 20 ft. (6 m) wide. The contract also includes approach road work that ties into the bridge.
Permatile Concrete Products Company of Bristol, VA is the fabricator of the replacement-precast structure. Phillip Burleigh, president and owner of Burleigh Construction, described the new bridge as “a series of upside down Us that are seven to eight feet wide and set side-by-side.” The ’U’ segments are then connected with post-tensioning cables and by a grouted keyway that is also precast.
Burleigh currently has five employees on the job site using Komatsu trackhoes for excavation work and Rockram hydraulic hammers to reduce shale rock. Later, the contractor will be renting a crane to install the precast structure.
According to George Romack, area construction engineer with VDOT’s Fredericksburg district, the bridge needed replacement for various reasons, but emphasized that, “It wasn’t unsafe.”
It just met the department’s rigorous criteria to deem it replaceable.
The Virginia Transportation Research Council, a cooperative organization sponsored jointly by VDOT and the University of Virginia in Charlottesville, in cooperation with the U.S. Department of Transportation Federal Highway Administration organized a review of “The Virginia Timber Bridge Initiative.”
The initiative suggested timber bridges might save money on highway construction and promote the forest products industry in rural Southside Virginia.
In its report, the commission concluded that although the timber bridges involved in the study are performing adequately, there is no suggestion that timber has been significantly accepted as a material used in bridge construction. The study also found that timber bridges have not demonstrated that they are economically competitive from an initial cost standpoint, and it is undetermined how cost competitive a timber bridge will be over its life cycle. Additionally, since there is a lack of industry presence in Virginia for timber bridges, it concluded that they are not economically feasible.
The commission’s final report stated, “This lack [of industry presence] also casts doubt on the ability of the Virginia timber bridge initiative to enhance economic development in the southside region of the commonwealth.”
As a result, VDOT is incorporating the steel beam timber deck bridge design less frequently nowadays. In the future, timber deck bridges will most likely be built in rural areas in which it wants to retain a rustic feel, which is the aesthetic appeal of a timber deck bridge. Furthermore, some localities prefer timber deck bridges that complement already existing historical buildings.
As for the future of timber deck bridges, that depends largely on cost competitiveness and acceptance by bridge engineers and construction companies.
“For new projects, we would not incorporate this type of design,” explained Romack. “I’m not saying we won’t use it. It is not the design of choice.”
The timber deck structures that are not scheduled for replacement, stated Romack, “are in good shape and performing what they are designed for.”
VDOT has closed Route 615 (Cropp Rd./Thompson Mill Rd.) to traffic for the duration of the bridge replacement project. In the meantime, drivers will use Route 614, also known as Spotted Tavern Road, as an alternative route until the project is completed, which is scheduled for June 1. CEG