Successes in Stewardship: April 2008 |
|---|
|
Federal Highway Administration
April 2008
The Buckland Bridge Replacement Project: Using Innovative Construction Techniques to Preserve a Historic District
Faced with public opposition to a necessary bridge replacement in the town of Buckland, the Virginia Department of Transportation (VDOT) successfully mediated a design solution to meet all parties' interests, including the preservation of a historic district, through the use of an innovative modular construction technique. Construction on the Buckland Bridge replacement began in January 2008 and is scheduled to be completed by September of this year. This issue provides an overview of the process that VDOT went through with local stakeholder groups to come to an agreement that all parties could support and introduces readers to the modular accelerated bridge construction technique used to replace the Buckland Bridge.
Buckland, Virginia, is a unique cultural landscape that has resisted fragmentation over time. It did not experience the changes that railroads, steam power, and Civil War Reconstruction brought to similar towns of that period. Buckland remains one of Virginia's most intact examples of 18th- and 19th-century mill-oriented settlement. Many of the earliest structures still standing in Buckland today were built from locally harvested native materials. The Buckland Historic District, which is listed in the National Register of Historic Places, includes the Civil War-era Buckland Mills Battlefield as well as one of the first turnpikes in the nation.
The Buckland Historic District is concentrated around the intersection of Buckland Mill Road and U.S. Route 15/29, which serves today as a major traffic corridor in the area. The southbound Buckland Bridge over Broad Run on U.S. 15/29 bisects the Historic District and carries an average daily traffic volume of 25,000 vehicles. The bridge was originally constructed in 1953, but after decades of use, bridge elements had experienced deterioration that could reduce the structure's ability to carry anticipated traffic loads. Engineers designated the bridge as "functionally obsolete" and "structurally deficient," a rating that demands corrective action to restore the bridge to a satisfactory condition. In 2000, VDOT proposed a replacement of the southbound deck to bring the bridge up to current standards and ensure safe public use. Under VDOT's initial proposal, the width of the new deck would increase from the current 33 feet to 44.6 feet, within the existing right of way, in order to meet the state and Federal standard of 40 feet curb to curb for two-lane rural and urban arterials (with a six-foot interior and ten-foot exterior shoulder). The additional deck width would enable both traffic lanes to remain open during construction. Maintaining traffic flows was an essential consideration for VDOT. Due to the current level of traffic congestion in Northern Virginia, any reduction in roadway capacity during peak hours would be unacceptable.
Under Section 106 of the Historic Preservation Act of 1966, Federal agencies must take into account the effects of their undertakings on historic properties. Agencies must consult with the appropriate State Historic Preservation Officer (SHPO) and additional stakeholders to determine if proposed actions will impact historic properties and discuss alternatives and/or mitigation strategies. In September 2005, the Federal Highway Administration (FHWA) determined that the proposed Buckland Bridge replacement project would have "no adverse effect" on the Buckland Historic District. However, the Virginia SHPO and the Buckland Preservation Society disagreed, stating that the project might result in cumulative impacts to historic properties. VDOT and FHWA engaged a number of stakeholders in a process to find design solutions that could resolve their concerns. These stakeholders included the Advisory Council on Historic Preservation (ACHP), Virginia SHPO, Manassas National Battlefield Park, American Battlefield Protection Association, National Trust for Historic Preservation, Civil War Preservation Trust, Piedmont Environmental Council, Buckland Preservation Society, and Prince William County.
During the Section 106 consultation process, the preservation groups and VDOT found themselves at an impasse, primarily over the width of the bridge deck replacement. VDOT and FHWA were focused on ensuring the replacement bridge's compliance with current Federal and state design standards and on sustaining normal traffic flow during peak hours. The consulting parties opposed widening the bridge beyond its existing 33 feet. The issue was finally addressed when, during a one-on-one meeting, a member of the Buckland Preservation Society explained to VDOT's bridge engineer that its opposition to the bridge widening was to prevent future expansion of U.S. 15/29 into a three-lane highway, which would greatly impact the historic nature of the area.
Responding to these concerns, VDOT developed an alternative bridge design that was able to meet VDOT's construction requirements, safety concerns, and project costs while also addressing the consulting parties' desire to maintain U.S. 15/29 as a two-lane road. The agreed-upon solution was a 38.6-foot-wide bridge (36 feet curb to curb with a four-foot interior and eight-foot exterior shoulder), six feet narrower than the original proposal. Although the new proposal required a design exception from FHWA and the state bridge engineer, it met the American Association of State Highway and Transportation Officials' (AASHTO) minimum standard for interior shoulder width and ensured that the exterior shoulder width could accommodate a disabled vehicle. The new alternative also called for utilizing an innovative construction technique that would allow both traffic lanes to remain open during peak daily traffic without requiring construction of a temporary traffic lane.
With modular accelerated bridge construction, bridge elements are constructed at an offsite location and then transported to the site for installation. Overnight, sections of the existing bridge are saw-cut, removed, and then immediately replaced by prefabricated bridge modules consisting of a concrete deck supported by two steel beams. A temporary joint is constructed to close the small gap between the existing bridge and the new module. The bridge can be reopened to traffic with full capacity before the arrival of peak traffic hours. The result is a significant reduction in construction time, fewer traffic disruptions, and a reduced environmental impact. The Buckland Bridge replacement has three spans, and there are four prefabricated concrete deck modules to cross the bridge width for each span. Over the course of just 12 nights, all sections of the existing bridge can be removed and fully replaced. Since construction will take place during nighttime hours, VDOT can keep both lanes of traffic on the bridge open during the day so peak traffic will not be impacted. Even at night, the new prefabricated modules allow one lane of traffic to remain open during construction hours (9 p.m. to 5 a.m.). Maintaining both travel lanes during peak travel hours will reduce the impact of the construction project on drivers in the area by 80 percent.1
While the modular construction technique does carry a cost premium compared to the use of traditional construction material, it can result in significant reductions in construction time and improve the traffic maintenance issues associated with construction. To this end, VDOT's Buckland Bridge replacement project received a Highways for LIFE (HfL) grant in 2007. This program gives awards to projects that advance safe, high-quality, longer-lasting highway and bridge infrastructure with use of innovations that speed construction to minimize construction-related congestion and increase user satisfaction. The HfL grant waived the 20 percent state match requirement (approximately $600,000) for the project, which allows VDOT to replace the bridge without using any state construction money.
The successful outcome of the Buckland Bridge reconstruction is due in large part to the willingness and flexibility of VDOT to work with consulting parties and to think outside the box in designing alternatives that minimize impacts on the Buckland Historic District. Two important lessons that emerged from the Buckland Bridge consultation process are:
The modular construction technique's ability to lessen the impacts of construction projects on commuters and the environment is a compelling reason for its use in future projects. Construction on the Buckland Bridge replacement began in January 2008 and is scheduled to be completed by September 2008. The outcome of this project will provide VDOT with valuable insight on how to apply the modular construction technique to future small-scale projects.
Sources
Contact InformationNicholas J. Roper, P.E. District Structure & Bridge Engineer Northern Virginia District Virginia DOT Chantilly, VA 20151 703-383-2117 Nicholas.Roper@vdot.virginia.gov MaryAnn Naber Federal Preservation Officer Federal Highway Administration 1200 New Jersey Ave, SE Washington, DC 20590 202-366-2060 MaryAnn.Naber@dot.gov |
Look What's New!NEW SECTION 4f RULE: FHWA and FTA recently published a Section 4(f) Final Rule in the Federal Register to help clarify the 4(f) approval process and simplify its regulatory requirements. The Final Rule is in response to the directive of the Safe, Accountable, Flexible, Efficient Transportation Equity Act (SAFETEA-LU); it incorporates modifications to the existing 4(f) rule and assigns the reorganized 4(f) section to a new location in the FHWA regulations (23 CFR 774). NEW ARTICLE ON PLANNING ENVIRONMENT LINKAGES (PEL): The March/April edition of Public Roads Magazine features an article on Planning and Environment Linkages (PEL). TELL US WHAT YOU THINK: Do you have a newsletter topic you'd like to read about? Are the newsletters helpful? Your feedback is wanted! Please send any comments or questions to esnewsletter@volpe.dot.gov. 
|
|
|