Interstate 5, State Route 526 to U.S. 2 Widening | Everett, WA

To alleviate traffic bottlenecks, WSDOT contracted WSP to provide construction designs for bridge widening along Interstate 5 and SR 526 lanes to US 2.


  • Washington, USA
  • United States


  • Washington State Department of Transportation (WSDOT)

Project Value

  • $160 million

Washington State has invested over $1.5 billion in special purpose lanes that form a crucial part of the central Puget Sound area’s highway system.

Approximately 310 lane-miles of a planned 320-mile freeway system were built, including the Interstate 5 (I-5), State Route 526 to U.S. 2 lanes.

To help eliminate sudden lane changes and improve a major traffic chokepoint on this stretch of highway, 10 miles of new high-occupancy-vehicle lanes on I-5 were added and two bridges were widened to increase safety and reduce congestion. A unique link slab design was incorporated into the two bridges to limit the effects of differential motion between the existing and new single-column piers during a seismic event. This special earthquake resisting system reduced the contractor's cost to build the bridges as part of this $160 million project.

 WSP provided the construction designs for the bridge widenings. In accordance  with WSDOT standards, Bridges 5/633 East and West were designed with WF58G (58-inch in-depth) and WF42G (42-inch in-depth) girders. Whe WF42G girders were necessary to maintain vertical clearance to the BNSF Railway tracks under the bridges. The work increased the roadway deck width of the bridges by 28 feet, from 48 feet to 76 feet.