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SR 99 AWV Holgate to King – Atlantic Street Bypass

SR 99 AWV Holgate to King – Atlantic Street Bypass

Improving traffic congestion for freight and commuters
Location
Seattle, Washington
Client
Washington State Department of Transportation
Designer
Washington State Department of Transportation
Contract Value
$29.3 Million
Completion Date
2014
Market Sector
Roadways & Bridges
Capabilities
Self Performance

As part of the SR 99 Alaskan Way Viaduct Replacement Program, the Atlantic Street Bypass provided a grade‐separated bridge over SR‐99 and the railroad tracks to connect the Port of Seattle Terminal 46 facility to SR 519. 

In this alignment, train activity often blocked traffic for extended periods. This not only slowed freight traveling to and from the Port of Seattle—it could also create traffic congestion stretching into Seattle's streets and Interstate 90. The new bridge helped freight and other drivers move faster and more reliably through the area and could save freight drivers as much as 20 minutes between the port and I-5 or I-90.

The bridge also provided an east/west pedestrian connection from Alaskan Way S. to S. Royal Brougham Way and S. Atlantic Street. Crews also completed improvements to the bicycle and pedestrian path on the west side of SR 99 between S. Atlantic and S. King streets.

The overpass is a three-legged, "h-shaped" bridge structure with a 40-foot inside radius. One leg of the bypass structure (H-1) begins at the intersection of Alaskan Way S. and S. Atlantic Street and continues northbound connecting with S. Dearborn Street via Alaskan Way S. The second leg (H-2) begins at the intersection of Colorado Avenue S. and S. Atlantic Street and terminates at an intersection with H-1.

The shared-use, 10-to-12-foot-wide bike/pedestrian path abuts the Port of Seattle Terminal 46 facility and divides into two paths beneath the intersection of H-1 and H-2. One path follows the west side of H-1 and the second path terminates along the east side of H-1 at S. Atlantic Street.