NW Market St Paving Project

Paving, sidewalk repair, curb ramp upgrades, water main replacements and stormwater drainage improvements.

June 24, 2020

Overview

NW Market St is an east-west arterial and considered a major truck street in Seattle's freight network. This 4-lane street is a critical piece of Seattle's arterial network. It is failing and needs repair. We will be doing a full concrete reconstruction to maintain access and support continued growth in the area, including multiple frequent transit routes and freight. This work also contributes to our levy goal to pave up to 180 lane-miles of arterial streets by 2024.

The scope of this project includes:

• Full concrete reconstruction of NW Market St between 24th Ave NW and 15th Ave NW (excluding intersections at 24th Ave NW and 15th Ave NW)
• Curb ramp upgrades and replacements
• Sidewalk repair
• Tree pit expansion
• Water main upgrades
• Stormwater drainage improvements

The Need for Construction

The pavement on NW Market St is failing structurally under the heavy truck and bus loading it carries. It is a major freight and transit street, carrying the #44 trolleybus, as well as the 17, 18, 29, and 40 routes to the west of Leary Way. Both the 44 and the 40 are busy routes prioritized for improvements under the Levy to Move Seattle (Transit-Plus Multimodal Corridors). The 2018 average weekday traffic volume on NW Market St is 20,400 vehicles per day.

Beyond vehicle access, this area is a business district with heavy pedestrian traffic; therefore, this project will install new crosswalks and ADA curb ramps, and repair areas of distressed sidewalk to provide safe access for all people to businesses along the extent of the project.

NW Market St in its current condition continues to be a major generator of pothole repair requests and complaints from the public asking that we repair the road as a matter of public safety.

If the street is not repaved as scheduled, the pavement will fail in the future, requiring emergency repair which would be more costly and could reduce our ability to plan the sequencing of the work to minimize disruptions to businesses.

The current project has been under development for more than a year and has undergone multiple agency wide reviews to ensure a high-quality design. The work has been coordinated with Seattle Public Utilities, Seattle City Light, and King County Metro to deliver a smooth construction process. Once complete the new street will be a durable concrete pavement that will not require any major work for 50+ years.  

What is the condition of NW Maket St?

SDOT uses the Metropolitan Transportation Commission (MTC) pavement management system and rating methodology to track the condition of Seattle's streets. The MTC rating method is based on the Pavement Condition Index (PCI) rating procedure developed by the US Army Corps of Engineers in the 1970s and described in ASTM standard D6433. It provides engineers and decision makers with a rational, objective measure of street condition. The procedure was designed to be repeatable and well correlated with the judgment of experienced pavement engineers.

The PCI method measures the occurrence of several pavement distress types and assigns a PCI score based upon the density (area affected) and severity of the observed distress. Structural, environmental and other types of pavement distresses are captured in this process. The PCI scale ranges between 100 and 0. A PCI of 100 represents a pavement completely free of distress; a PCI of 0 corresponds to a pavement that has failed completely and can no longer be driven safely at the designed speed. Pavement Condition Ratings (PCRs) are associated with ranges of PCI. The table below shows the range of PCI values to which each rating corresponds based on the ASTM D6433 scale.

Pavement condition ratings and pavement condition index ranges

Streets in "Fair" condition or above generally require only routine or preventive maintenance. When pavements reach a condition level of "Poor", they show notable deterioration and may be candidates for major maintenance or preservation work such as an asphalt overlay, concrete panel replacement, or diamond grinding. Streets in "Very Poor" condition or below have typically deteriorated to the point where potholes and other structural distress are widespread, and the pavement needs to be completely reconstructed.

The area weighted average PCI over the NW Market St project segment (15th to 24th Ave NW) is 30, corresponding to a PCR of "Very Poor" overall. Below is the breakdown by segment:

Final Design Project Map

Schedule

Thiis project has been paused. 

Get Involved

We're committed to engaging with the community throughout the life of the project. We want everyone to have the opportunity to continually engage with us and ask questions. Outreach is conducted throughout the planning, design, and construction phases and we encourage you to attend public meetings and engage with us online.

The Three Stages of a Project

1. Planning

    What we do: Collect traffic data, review plans and gather community experiences to define options.

2. Design
    What we do: We work with the community and produce a more detailed project design.

3. Construction
    What we do: We construct the project and keep the community informed on the latest construction updates, schedule, and expected impacts.

Funding

This project is part of SDOT's Arterial and Asphalt and Concrete (AAC) Paving Program. Design and construction of our paving projects, as well as the safety and mobility improvements shown, are funded by the Levy to Move Seattle, approved by Seattle voters in November 2015. We also seek additional funding through grants, when available. Learn more about the levy at seattle.gov/LevytoMoveSeattle. 

NW Market St Outreach 

Project Materials

To view a PDF of project-related materials, please click on the links provided below.

Design Phase

90% Design

• 90% Open house summary (Dec. 2019)
• 90% Project mailer (August 2019)
• 90% Channelization maps (Dec. 2019)
• 90% Open house display boards (Dec. 2019)
• 90% Open house poster (Dec. 2019)

30% Design

• 30% Channelization map (November 2019)
• 30% Project fact sheet (June 2019)
• 30% Pavement map (June 2019) 
• 30% Plan (June 2019)
• 30% Project mailer (June 29)

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