The Atkinson team constructed the SR-99 tunnel’s north access entrance and exit roadways from the portal structure at Harrison Street to north of the Mercer Street bridge as part of the Alaskan Way Viaduct replacement program. The team also built on- and off-ramps at Republican and Harrison streets and extended Sixth Avenue North from Harrison Street to Mercer Street.

After the new roadways and bridges were complete, the team demolished the existing SR-99 bridge over Broad Street. As part of their scope, the team also installed traffic signal, illumination, and ITS systems, and relocate existing utilities, including water, storm, sewer, and high voltage electrical systems.