ENR Northwest 2024 Best Projects
Award of Merit Highway/Bridge: SR 520, 148th Avenue NE Interchange
Photo by Nicholas English
SR 520, 148TH AVENUE NE INTERCHANGE
Redmond, Wash.
Award of Merit
Submitted by: Granite Construction Co.
OWNER: Washington State Dept. of Transportation (WSDOT)
LEAD DESIGN FIRM: HNTB Corp.
GENERAL CONTRACTOR: Granite Construction Co.
A new direct access off-ramp from eastbound SR 520 carries traffic to the Overlake Village area in Redmond through a 130-ft-long cut-and-cover tunnel running beneath 148th Avenue Northeast. Project scope also included two roundabouts and several new city streets: Northeast Hopper and Northeast Shen streets and Lumiere Avenue.
This solution helps drivers bypass the busy 148th Avenue Northeast/Northeast 24th Street intersection and establishes a direct route to destinations along and beyond 152nd Avenue Northeast.
Technology played a critical role on this project, from GPS to CAD, Agtek and PlanGrid. These applications helped the team identify constructibility challenges, propose solutions and ensure everyone in the field was up-to-date. Some of these solutions included shifting and relocating piles for a planned soldier pile wall to avoid a conflict with an overhead guideway and quickly redesigning noise walls when issues arose without impacting the schedule.
To minimize traffic impacts along 148th Avenue NE while constructing the 130-ft cut-and-cover tunnel, the contractor utilized 30-ft-deep shoring adjacent to live traffic, allowing crews to build the tunnel in two phases. This process also required excavating around and beneath existing utilities, including a gas line, to ensure there were no interruptions in utility services.
Crews placed more than 3,800 cu yd of concrete throughout the project’s duration and completed the bypass 34 days ahead of schedule in December 2023.
