SR 99, Demolition, Decommissioning, and Surface Street Project

Contract summary

This project will demolish the approximately 1.4-mile-long SR 99 Alaskan Way Viaduct (AWV) structure from the vicinity of South Dearborn Street to the south portal of the Battery Street Tunnel. This structure passes through the city of Seattle, adjacent to the waterfront. The AWV was completed in 1953, and is a double deck, predominantly reinforced concrete structure. The project will include the following:

Demolition of the approximately 1.4-mile-long AWV structure, including all associated ramps. The AWV Bridges 99/540 NB and 99/540 SB consist of three span frames that support two roadway decks. The frames generally span over parking areas and city streets, and in some locations, are in close proximity to occupied buildings. The concrete reinforced frames are fixed, monolithic (moment resisting) structures.

Demolition of one on-ramp located at Columbia Street and one off-ramp located at Seneca Street. Ramp roadways are typically supported by prestressed concrete girders. Demolition of columns and footings to a depth of 5 ft. below finished grade. Demolition of approximately 210 ft. of two steel girder structures spanning the Burlington Northern Santa Fe Railroad tracks.

Other work elements include, but are not limited to, grading, paving, sidewalk, storm drainage, water quality, traffic signals, maintenance of traffic, signing, pavement marking, illumination, landscaping, and protection of public and private property and infrastructure. In addition, the project will decommission the Battery Street Tunnel, re-grade Aurora Avenue between Harrison Street and Denny Way, and connect the surface streets at John Street and Thomas Street.