This project replaced an existing five-span 79-foot-long timber slab bridge on timber pier bents and concrete abutments. The timber superstructure and pier bents exhibited severe timber decay, and the pier bents were prone to debris accumulation. Therefore, the bridge was slated for complete replacement.
Fisher Associates evaluated multiple superstructure types for the replacement and performed a detailed hydraulic analysis using HEC-RAS to size the bridge opening. Removal of all five piers for the replacement enabled the design of a shorter, single-span bridge. The new bridge was constructed within the existing opening by constructing the abutments in front of the existing abutments. The footings were keyed into the rock at the creek bed to ensure the structure is protected from scouring in the high-velocity creek. Northeast Extreme Tee (“NEXT”) beams, Type D, were used as primary members with an asphalt wearing surface.
The approaches were reconstructed to correct geometric deficiencies in the roadway profile and to provide a smooth transition to the newly constructed bridge. Although the existing structure carried gas and sanitary sewer lines, Fisher was able to expedite construction by working with the gas company to have their line relocated off of the bridge, in the rock creek bed, prior to construction. The sanitary line needed to remain on the structure but was temporarily relocated during construction to accommodate the construction activities. An off-site detour was detailed to allow expedited construction sequencing.
As part of the project, Fisher Associates provided environmental services that included NEPA/SEQRA documentation; social and economic considerations; general ecology; threatened and endangered species; flood plains; groundwater; surface water; wetlands; navigable waters; historic and cultural resources; farmlands; HW/CM and ACM; and preparation of permit applications to the NYSDEC and USACE for wetland activities. The NYSDEC permit included provisions for restriction of in-water work to reduce or eliminate impacts to a state-listed species.
The result of these environmental screenings was incorporated into the Design Approval Document. Fisher Associates held a public meeting where those citizens impacted by the project were able to provide comments. Final Design was completed with the creation of detailed plans, specifications, and engineer’s estimate. Fisher also performed the bid analysis, recommendation of the award, and notice of award. Throughout construction, Fisher Associates continued to support the County by providing construction support and full-time construction inspection.