YESLER BRIDGE REHABILITATION PROJECT, YESLER WAY OVER 4TH AVENUE S.
IMCO rebuilt the historic Yesler Bridge in downtown Seattle, removing the existing bridge and constructing a new pier foundation and abutment that supports the lateral pressure of the arch at the end of the bridge. IMCO performed rehabilitation of the existing abutment and historical elements, building a new steel girder bridge, and making improvements to sidewalks, roadway surfaces, and existing railings for improved pedestrian and traffic safety. Historical elements such as decorative pedestrian railings, fascia girders, ornamental corbels, girder columns and cladding, were carefully removed, rehabilitated, and re-incorporated into the new construction to ensure the key historical features of the bridge were preserved.
The Yesler Way Bridge is located in the Pioneer Square Historic District of Seattle and serves as the gateway to downtown. The 100-year-old structure was a non-redundant, three-span superstructure. Meaning if a steel column would have buckled from a vehicle crash, bridge collapse would have been likely. The columns were less than 11 inches from the 4th Avenue sidewalk curbs, with no other barrier from potential vehicle collisions. The bridge was constructed before seismic design codes were in place, and in the event of an earthquake, collapse would have been likely.
The bridge also connects traffic spanning east to west across Interstate-5 and is a vital route for residents, commuters, and workers. The primary goals for the project were to improve traffic patterns and increase vehicle and pedestrian safety. The Terrace Street intersection was upgraded by improving the visibility when vehicles entered the intersection. Parking was reduced on the bridge deck and sidewalks were enlarged to facilitate pedestrian patterns across Yesler Way and Terrace Street. Improved lighting, widened sidewalks, and the addition of a bike lane under the bridge on 4th Avenue, improved safety for bikers and pedestrians traveling on 4th Avenue.
Preserving the historical elements of Yesler Bridge was a critical priority for the project. The Yesler Way Bridge project uniquely balanced historic preservation while providing a safer, better functioning, and more durable bridge. Preserving the iconic bridge’s key historic features was critical because the bridge is a visual gateway and landmark for the City’s historic districts.
Yesler Way and Terrace Street were closed during the life of the project, but vehicle and pedestrian traffic on 4th Avenue were maintained, as well as access to existing buildings located near the work area. The project required tough scheduling and tight work areas, while keeping existing facilities operating during construction.