Columbia St 2-Way Transit Corridor

What's happening now?

Work on the Columbia St 2-Way Transit Corridor continues.

This past month

  • We worked with our partners at Seattle City Light and Seattle Public Utilities to replace the water main from 1st Ave to 2nd Ave
  • We started replacing the water main on Columbia St, from 2nd Ave to 3rd Ave
  • We reconstructed the north side of Columbia St from 1st Ave to 2nd Ave with new, concrete panels designed to handle the additional weight of bus traffic

Next month

  • Traffic control and lane closures will remain in place
  • We’ll finish paving the north side of Columbia St from 1st Ave to 2nd Ave and begin paving the north side of Columbia St from 2nd Ave to 3rd Ave
  • We'll install new signals and reconstruct sidewalks with ADA approved ramps on the north side of Columbia at the 1st Ave and 2nd Ave intersections
  • We'll finish replacing the water main from 2nd Ave to 3rd Ave. This will conclude our water main work for this project
  • We'll prepare the south side of Columbia St from 1st Ave to 2nd Ave for road reconstruction

Construction impacts

  • Typical work hours are 7 AM - 4 PM, Monday through Friday, with some overnight and weekend work
  • On-street parking restrictions
  • Lane closures (2 lanes to remain open)
  • Occasional weekend full street closures
  • Occasional driveway and alley closures
  • Temporary sidewalk and crosswalk closures
  • Access to businesses, residences, and other properties will remain open
  • Construction noise, vibrations, and odors
  • All work is weather dependent and subject to change.

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.

Spring 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