I-405 Widening and Express Toll Lanes, NE 6th St. to I-5

Washington State Department of Transportation

Bellevue to Lynnwood, Washington

1-405 bridge

This $155.5 million project provides one additional lane in each direction on I-405 from NE 6th Street in Bellevue to SR 522 in Bothell. In addition, a new northbound bridge will be constructed between NE 160th Street and SR 522. The project involves retaining walls, noise walls, two bridges, and stormwater treatment and detention facilities. Hart Crowser, as part of the design-build team, is the lead geotechnical engineer. Hart Crowser authored and provided input on several Alternative Technical Concepts (ATC) that led to the successful bid of the project, including realignment of horizontal and vertical profiles to avoid a series of heavy structural walls that would have been necessary to stabilize major cuts in a historical landslide area.