WSDOT – I-405 Express Toll Lanes with Braided Ramps Design Build Project
- Services Bridge Engineering, Structural Engineering, Transportation Engineering
- Market(s) Bridges, Roadway, Transportation/Transit
- Owner Washington State Department of Transportation
- Contractor Flat Iron
- Team Seattle, WA
Working closely with WSDOT, KPFF was the lead civil and structural engineer for a fast-tracked design-build project that added one lane in each direction of I-405 to create a two-lane Express Toll Lane System from NE 6th Street to SR 522. KPFF designed all the structures and a significant portion of the paving and drainage for this project. KPFF engineering a grade-separated flyover ramp system for the NE 160th Street northbound on-connection to I-405/SR 522 and the northbound off-ramp to SR 522; an upgrade of the entire corridor to meet current stormwater runoff requirements; re-striping of 12 miles of I-405 to accommodate the widening; over 50 new sign and tolling gantry structures, and 5,000 linear feet of new retaining and noise walls.