Construction is scheduled to begin Monday on the eventual conversion of Columbia Street from a one-way street to a two-way transit corridor between First and Third Avenues.

Columbia Street will provide a vital link for buses traveling through downtown on Third Avenue once the State Route 99 tunnel opens and transit lanes on the Alaskan Way surface streets are constructed in both directions between Dearborn Street and Columbia Street. A new eastbound transit lane, which won’t open for a few years, will connect buses traveling from the State Route 99 off-ramp in SODO.

The first phase of construction on Columbia Street is expected to take about six months, and will entail reconstructing the street between First and Third Avenues with concrete; replacing a water main pipe, installing new traffic signal poles and altering curb lines for future configuration.

Initially after the first phase of construction ends in June 2018, Columbia Street will function as it does today. Bigger changes won’t happen until WSDOT opens the State Route tunnel in early 2019. Once that happens, the Columbia Street on-ramp will be permanently closed and buses will be routed via interim pathways.

After the Columbia Street on-ramp is demolished, the City will reconstruct the second phase of Columbia Street between First Avenue and Alaskan Way as part of the Waterfront Seattle Main Corridor project, with Columbia Street reopening to traffic in late 2020.

King County is funding reconstruction of Columbia Street between First and Third Avenues. Columbia Street between First Avenue and Alaskan Way will be reconstructed as part of Waterfront Seattle’s Main Corridor project, which also includes dedicated transit lanes on Alaskan Way south of Columbia Street that will be operational once that project is completed in 2023.

Work hours will be from 7 a.m. to 5 p.m. on weekdays on the first phase, with some overnight and weekend work. On-street parking will be prohibited on Columbia Street from First Avenue to Third Avenue. Work also may entail temporary sidewalk and crosswalk closures.

At least two lanes of Columbia Street will be open during construction.

More information is available at the Seattle Department of Transportation‘s website.