Photo courtesy of Guy F. Atkinson Construction Atkinson’s proposal for a concrete bridge saved time and money when steel costs were high. Bridge segments were built off site and assembled overnight.

One of the most remarkable aspects of the project is that it included a segmental bridge — one built in segments and assembled on top of a column, building outward.

Atkinson proposed this method to replace the Washington State Department of Transportation’s plan for a steel tub bridge. A segmental bridge, built with concrete, saved the company and state money at a time when steel costs were high, and it was the first time this method was used on a WSDOT project.

Crews built individual segments off site and assembled them above the freeway overnight. Coordination between day shift and night shift added to the complexity, and so did the fact that each segment was different and required custom work. The viaduct was $14 million under budget and completed several months ahead of schedule.

Crews built 10 new bridges, including the segmental overpass connecting northbound Interstate 5 to westbound state Route 16. The bridges, constructed from new approaches on 77 piers, span more than 7 acres.