CR21 Bridge (Dean Bridge) Replacement
Town of Hillsdale, Columbia County, New York
The CR21 Bridge (Dean Bridge) over a tributary to the Roeliff Jansen Kill was a 28 ft. long single-span bridge consisting of a concrete-encased steel beam superstructure on concrete abutments founded on spread footings. The existing bridge deficiencies included poor stream alignment resulting in scour, cracked and spalled concrete abutments, non-standard bridge rail, and extensive beam deterioration. The replacement structure is a single span prestressed concrete adjacent voided slab superstructure on integral abutments with standard 10 ft. wide travel lanes and 4 ft. wide shoulders. The span increased to 51 ft. to better match the stream geometry and to ensure that the 100-year storm event could be accommodated without overtopping the bridge. Creighton Manning was responsible for preliminary and final bridge design phases, survey, hydraulic analysis, and construction inspection. The new structure meets the current NYSDOT standards with a 50+ year design life and improves the scour susceptibility and hydraulic opening to convey the 50-year design flood event.