H&H provided bridge design services, including replacement or rehabilitation design of bridge structures, geotechnical design services/soil borings, right-of-way appraisals/documentation, obtaining permits, roadway design, pavement design, and ADA pedestrian facilities for the replacement of the bridge.
Work included storm drainage, street lighting, electric duct banks, traffic control, erosion and sediment control, surveys, landscaping, planning, environmental site assessments, NEPA clearance, writing specifications, developing cost estimates, preparing advertisement contract documents, shop drawing reviews, construction phase services and reviews, coordination with utility/railroad owners and other outside agencies, and other related civil and structural engineering tasks.
The hydrologic analysis required modeling of over 80 square miles of drainage basin and flood routing through several miles of river channel and reservoirs. HEC-HMS was utilized to model hydrologic conditions and perform dam modeling at the analysis point, and then HEC-RAS was used to model riverine conditions at the bridge crossing. A hydraulic report was submitted. Scour assessment was completed utilizing FHWA’s HEC-18, HEC-20, and HEC-23 methodology.
The project was unique because it is located along a river between two significant dams. Built in 1922 and rehabilitated in 1982, the prior bridge was a 437-foot-long, five-span deck truss structure. It was replaced with a new two-lane, multi-span steel girder bridge. Multiple alternative alignments were reviewed, and the selected alternative alignment was located downstream from the dam.
