Columbia St 2-Way Transit Corridor

What's happening now?

Major construction is complete! 

We have completed all major construction activities on Columbia St. We have reopened Columbia St between 1st Ave and 3rd Ave. Throughout the remaining of the year, you may continue to see crews onsite wrapping up minor construction activities. Remaining work includes traffic signal wiring, street lighting installation, and new signage installation.

Columbia St between 1st Ave and 2nd Ave looking west

Project Overview

The Alaskan Way Viaduct Replacement Project is underway and expected to be complete in a few years. When the viaduct is demolished and the new tunnel opens to traffic, our regional transit pathway from West Seattle and southwest King County will need to be rerouted onto surface streets.

To accommodate this change, the City of Seattle and King County Metro have developed a plan for a transit pathway on Alaskan Way and Columbia St to get buses to and from the 3rd Ave transit spine. A grant from the Federal Transit Administration is paying for part of this work.

Today, Columbia St is a 1-way street heading westbound that connects to a viaduct on-ramp at 3rd Ave. Our project – the Columbia St 2-way Transit Corridor – will rebuild the segment between 1st Ave and 3rd Ave. The segment between 3rd Ave and Alaskan Way will be rebuilt and converted to 2-way operations as part of the Waterfront Seattle project.

Once done, there will be a new cement street that can handle the higher weight of buses and an eastbound lane for transit and local access to move thousands of people a day into downtown Seattle on our new, post-viaduct transit pathway.

Project Details

The project area is Columbia St from 1st Ave to 3rd Ave. Work includes complete street reconstruction, which means we’ll remove the current asphalt and street base and pave the street with cement. Intersections will be left as-is for now. Some new traffic signals will be added to the intersections to prepare for future eastbound traffic.

The newly paved street will be striped the same way it is today. Two-way operations will only begin once the viaduct is removed and the new streets under it are built and ready for transit in a few years.

While the street is open, our partners at Seattle Public Utilities will replace the water main pipe.

Project Details Map

Project Details Map

Project Background

This project is being constructed in preparation for the Alaskan Way Viaduct Replacement Project, which is being led by the Washington State Department of Transportation in partnership with the Federal Highway Administration, City of Seattle, Port of Seattle, and King County.


Fall 2017

Construction begins in December.

Summer 2018

Construction ends.


Funding for this project comes from a grant from the Federal Transit Administration managed by King County Metro.


Work Zone Map (January 2018)

Factsheet (December 2017)

Postcard (December 2017)

Full project plans - large file (December 2017)

SDOT Columbia 2-Way Traffic Advisory


Greg Spotts, Director
Address: 700 5th Ave, Suite 3800, Seattle, WA, 98104
Mailing Address: PO Box 34996, Seattle, WA, 98124-4996
Phone: (206) 684-7623

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The Seattle Department of Transportation (SDOT) is on a mission to deliver a transportation system that provides safe and affordable access to places and opportunities for everyone as we work to achieve our vision of Seattle as a thriving, equitable community powered by dependable transportation.