Natural Bridge, Virginia: Complementary Geotechnical Investigation and Analysis Methods for Mobility Planning

Natural Bridge, in Rockbridge County, Virginia, is a geological arch carrying U.S. Route 11 over Cedar Creek. The area has significant historical and cultural importance; it is listed on the National Register of Historic Places and is a Virginia Historic Landmark. Until 2015, the arch and area below were privately owned and operated, with only the pavement structure of U.S. Route 11 held by the Virginia Department of Transportation. Since then, the arch and area below have been leased to the Virginia Department of Conservation and Recreation, potentially transferring liability to the Commonwealth. As part of the Commonwealth's due diligence and to help ensure that the arch is preserved for future generations, the Department of Transportation, in partnership with Radford University, completed a comprehensive, non-invasive geological and geotechnical investigation in 2017 and 2018. A complementary variety of geophysical, laser, optical, seismic, and traditional geological methods of study were used to allow for integrated data analysis. The investigation revealed potential risks to the integrity of the arch, which may eventually reduce its suitability for use as a transportation corridor. The investigation methodology allowed planning for protection of the environment, cultural resources, and local economies while avoiding any potential damage to the arch. As of the date of this article, plans are under way to relocate U.S. Route 11 onto an alternate alignment entirely, thereby helping to preserve this valuable cultural, historical, and geological asset.