H&H was responsible for providing accelerated engineering design services for the replacement of the New Croton Dam Spillway Bridge, an integral part of the historic New Croton Dam in Westchester County, and adjacent to Westchester County’s Croton Gorge Park.
A new 200-foot open spandrel steel arch bridge was designed to fit into this historic, complex and context-sensitive site. Our design incorporated historic details captured from the adjacent New Croton Dam, as well as the original structure, such that the modern span replicated the elegance of 1904 bridge, yet used modern efficient and durable materials to complete this timeless structure.
H&H provided engineering services which included: topographic survey; in-depth structural inspection; preliminary and final design; Environmental Assessment Statements (EAS); federal, state and local wetland permitting; and construction support services. The entire design, including all permitting and approvals, was completed in three months. As part of these services, H&H performed structural load capacity analysis of the dam’s roof/roadway supporting structure which carries the bridge’s approach slab to determine the replacement details for the new bridge approach slabs. H&H provided structural analysis services to determine the new skewback support locations that support the loadings from the proposed 212-foot roadway deck and supporting arch structure into the north and south masonry abutments.
H&H also prepared a seismic retrofit to the dam and bridge supports which included vertical and angular rock anchor design into the north and south cyclopean masonry abutments. Masonry repointing was performed within the construction limits to restore the historic character of the dam and adjacent bridge. Coordination was also required with NY Dam Safety Section of the State Department of Conservation to confirm the proposed substructure design accounted for the overtopping the bridge support elevations during peak PMF flows from the adjacent New Croton Reservoir.