Construction Engineering

38th Street (Franklin Ave.) Bridge

Location: Astoria, Oregon

The Franklin Avenue (38th Street) Bridge is located in Astoria, Oregon. Franklin Avenue crosses over 38th Street in the Adair-Uppertown Historic Inventory Area and is the sole means of access to approximately 40 homes. The neighborhood has a great deal of character and history. Several locally designated historic residences are adjacent to the bridge and approach roadway. The original bridge was a nine-span, 217-foot-long timber trestle bridge that was 30 feet wide with a narrow sidewalk on the north side. The replacement structure is a two-span, 180-foot-long bridge on drilled shaft foundations that are 40 feet wide with sidewalks on both sides of the bridge. The replacement bridge incorporated architectural treatment of the abutments, interior bent, and the bridge rail to complement the historic district.

DEA was retained to provide project management; bridge, roadway, and traffic design; and environmental services. DEA also provided construction contract administration, engineering support, and inspection services. This project is located in an active landslide. The design team monitored slide movement magnitude and direction. A unique design was developed to provide the bridge with the ability to accommodate projected earth movement from the slide. Key aesthetic features were also incorporated to support continuity with community character. To maintain neighborhood access and avoid the need for additional right-of-way, the bridge was replaced utilizing staged construction with signal-controlled, one-way traffic.