The Ramsdell Road Bridge in Henniker, New Hampshire was constructed in 1937 as a Works Progress Administration project during the second phase of the New Deal.
The bridge is a historic Warren Through-Truss of riveted construction with a reinforced concrete deck and outboard cantilevered sidewalk. Rehabilitation design of the bridge began with the intent of restoring the structure and maintaining its historic fabric and integrity, while increasing the live load capacity from the original H15 design load to an HS20 design load. Utilization of an innovative bare exodermic deck with lightweight aggregate concrete and replacement of key structural members were required to increase the live load capacity. The floor system and bottom chords were replaced in their entirety. Replacement of two rocker bearings and partial replacement of three main built-up end diagonal members was also required. Existing green lead paint was removed and replaced with a new three component system in grey, to match the original color.
The bridge is located in a United States Army Corps flood storage area, meaning that at any time, water in the Contoocook River could rise by approximately 16 feet to store water during large rain events, bringing the water level up to the portal bracing elevation. This $1.5 million project is an example of how historic preservation and modern transportation needs can simultaneously be met.
Hoyle Tanner presented a paper on this project at the international Bridge Conference in Pittsburgh, PA.
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