Pacific Avenue Overpass

Engineering Services (1998 – 2001)

The Pacific Avenue Overcrossing, a five-lane bridge located in the heart of downtown Everett, Washington, was constructed to eliminate an at-grade railway crossing that was causing major delays for the 13,000 drivers using Pacific Avenue daily. There were safety concerns too, as 30+ trains use this mainline route each day. The overcrossing was also needed to provide direct access to the new $47 million Everett Station, a multimodal center that serves as the northern terminus for regional passenger rail service to the Seattle Metro area.

The $17 million project has been a tremendous success and has already won two awards: American Council of Engineering Companies of Washington’s award for best design in 2003, and Precast/Prestressed Concrete Institute’s Design Award in 2002, taking first place among 148 other entries.

MACTEC’s role included preparing the construction documents for the bridge and providing engineering support during its construction. The clients, Sound Transit and the City of Everett, were simultaneously building a five-story transportation hub, Everett Station, in close proximity to the bridge. To ensure efficient coordination of the two projects, MACTEC worked closely with the Everett Station design team throughout the process.

The overcrossing consists of a 750-foot-long, 78-foot-wide main span that crosses the Burlington Northern Sante Fe (BNSF) rail line, and a 200-foot-long, 64-foot-wide, four-lane side ramp that provides access to surface streets feeding the multi-modal station. The bridge’s superstructure is composed of 58 precast, prestressed tub girders with cast-in-place concrete decking, and its substructure is composed of concrete column/shaft bents.

The bridge features a transversely post-tensioned cantilevered bent that carries two traffic lanes, a continuous end-to-end post-tensioning scheme, and seismic design considerations on the interface between the ramp and the main bridge. Sidewalks and at-grade frontage roads were constructed to maintain pedestrian and vehicle access to local businesses and surface streets.

As the prime engineering consultant for the project, MACTEC provided a type, size and location report; plans, specifications and estimates; and construction management. This involved coordination and permitting from BNSF, right-of-way acquisition, design of arterial approach roads, design of parking facilities, grade separation design, storm water drainage design to connect with the existing drainage system, and traffic signal and illumination design.

Environmental permitting included a SEPA checklist and Endangered Species Act analysis. MACTEC also participated in extensive public involvement to represent the community’s interests, which included incorporating local artists’ aesthetic design features into the overall design of the structure.