Northgate Pedestrian and Bicycle Bridge

Updated: August 4, 2020

Project overview

The Northgate neighborhood is a major residential and employment destination that continues to grow. With the completion of Sound Transit’s Link light rail station in 2021, the neighborhood is poised to become one of the region’s most active transit hubs. Today, a 10-lane interstate divides the neighborhood, and to walk between North Seattle College and the existing transit center is 25 minutes or more.

Connecting communities on the east and west sides of I-5 in Northgate

We designed a new, accessible, all ages and abilities pedestrian and bike bridge over Interstate 5 (I-5) in Northgate. The Northgate Ped/Bike Bridge will improve access to communities, services, and opportunities on the east and west sides of I-5 in Northgate and Licton Springs, helping knit together a historically divided area. It’ll also reduce travel time for people walking and biking between the east and west sides of I-5. When complete, the bridge will help connect the neighborhood’s thriving job and retail centers with the rest of the city and region.

The new bridge will span roughly 1,900 feet over I-5, landing at North Seattle College on the west side and at 1st Ave NE and NE 100th St, near the future light rail station, on the east side.

The project consists of four main parts:

• Bridge spans over I-5
• Western approach between North Seattle College and wetland area, connecting to College Way N and N 100th St
• Eastern approach between I-5 and 1st Ave NE at NE 100th St, near the King County Transit Center
• Multi-use path along 1st Ave NE

The project will benefit the area by providing:

• A new connection over I-5, decreasing travel times for people walking and biking between the 2 sides of the highway
• Safety improvements and access for people walking and biking throughout the Northgate area
• Better access to regional transit at the King County Transit Center and future Link light rail station, resulting in increased use of transit facilities
• Improved connections between the Northgate retail center for its employees and customers and for residents and visitors to other nearby amenities, such as parks and medical and social services

Project location

Design renderings

The view from I-5 traveling north.

The user experience walking or biking across the bridge.

A view of the bridge, looking east.

Recent cost-saving changes

We formed a new design team in 2016 to help reduce project costs and meet project goals. The team developed a bridge design that includes the following cost-saving changes and design improvements:

Finally, an added benefit of the revised design is enhanced user experience with features such as a wetland wildlife overlook and a view of arriving light rail trains at NE 100th St.

What we’ve heard through design

Based on community input throughout the project, we know there’s interest in:

• Minimizing environmental impacts of the bridge by making sure, for example, that the project doesn’t disturb wildlife during construction and ensuring the bridge’s drainage system (for stormwater) is designed to enhance wetlands on the west end
• Ensuring safety and security of all bridge travelers
• Wayfinding and traffic control
• The experience of people biking and using other wheeled devices (e.g., scooters, wheelchairs, strollers, rollerblades, suitcases, etc.)
• Connecting the bridge to other infrastructure, including neighborhood bike routes
• Separating or managing modes of traffic on the bridge

Other topics of interest included the project’s cost, the bridge’s durability, and maintaining vegetation.

We value the community input provided to date and thank you all for your continued interest.

Tree mitigation plan

Throughout our preconstruction outreach, the project team heard from many people asking about our tree mitigation plan. We will be removing 93 trees during this project, and we will be planting 464. The map below shows the full details. You can click on the map to download a PDF of the plan. 

Designing for a safer bridge

During each phase (planning, design, and pre-construction) of public outreach, we heard that bridge safety is a priority for all bridge users. The sections below outline how safety is incorporated into all aspects of the bridge's design.

Design and accessibility

Throughout the design process, we used an approach called Crime Prevention Through Environmental Design (CPTED). This approach is based on the idea that people's behavior within an urban environment is influenced by the design of that environment.

CPTED strategies include things like providing ample lighting to avoid blind spots, maximizing sight distance and visibility (sometimes called "passive surveillance"), and using materials that promote easy maintenance. This strategy also aims to create spaces that give a sense of ownership of public space and a sense of shared responsibility for personal security.

There are several safety elements on the bridge, including:

• Minimal surface area for vandalism
• Overhead pedestrian lighting
• Emergency call boxes 
• Pedestrian guardrails
• Lighting on handrails 
• Throw fences

The City of Seattle strives to make city programs, services, and activities equally accessible to all. Our bridge design complies with 2010 ADA Standards and includes the following features:

• A bridge slope of 4.3%, except between the Sound Transit mezzanine and the NE 100th St level, which is 8.1%. This section has ADA-compliant handrail grips and 1.8%-slope landings every 30 feet to provide resting places.
• Elevator access via the Northgate Station Garage, including where the bridge connects to the Northgate Link light rail station, during normal hours of operation.
• Curb ramps along 1st Ave NE and NE 100th St, where the bridge spur lands.
• Accessible pedestrian signals at the intersection of 1st Ave NE and NE 100th St, which will offer push-button activation, audible signals, and vibrations to indicate when it's safe to cross the street. 

Materials

All bridge materials and connections will go through intensive testing during construction, including the spans across I-5, which will undergo rigorous quality assurance testing during fabrication, assembly, and installation. The trusses of our bridge will be made of steel, a common and proven material and design for hundreds of bridges across the nation.

Life expectancy

Our bridge was required to meet the 75-year design life expectancy criteria consistent with the American Association of State Highway and Transportation Officials (AASHTO) design codes. Not only does our design meet this standard, it's expected to exceed a lifespan of more than 100 years with routine maintenance during its service life. 

Environmental 

We selected vegetation and greenery around the bridge with safety in mind. Creating park-like qualities on the trails and spaces near the bridge will provide a comfortable and enjoyable atmosphere and a "sense of place" for all users. Examples of this can be seen on the west side with a wildlife overlook, and on the east side where we're proposing a "gallery forest," or screen of tall and narrow trees between the bridge and the freeway, providing relief from views of the freeway and filtering air quality.

Additional environmental features include:

• Planting low-growing shrubs and bushes around the bridge
• Trimming, thinning, or removing existing trees and undergrowth to create open sight lines
• Carefully designed plantings on the west side of the bridge so that pedestrians on the landing will have a clearer view of North Seattle College (NSC), and those on the NSC playing field and in the parking lot will see bridge users approaching  

Schedule

We expect construction to begin early 2020, and to be complete in fall 2021, prior to the opening of the Link light rail station in September 2021.

Funding

We’ve secured funding from various sources in addition to the voter-approved Move Seattle levy. These include SDOT, Sound Transit, Washington State, and additional local funds.

Stay informed

Email is the best way to stay up to date on the project during the entire construction process. 

Click here to sign up to receive project email updates

Park and Ride Information

Click this link for more details about which Park and Rides are open and available throughout construction.

Outreach events

Materials

January 2020

• Winter 2020 Drop-in Summary

December 2019

• Construction flyer - English
• Construction flyer - Chinese
• Construction flyer - Spanish 
• Construction flyer - Russian
• Construction flyer - Vietnamese
• Construction notice
• North Seattle Park & Ride closure notice
• Final Design flyer

Environmental Review

• NEPA DCE
• Environmental Justice Discipline Report
• Hazardous Materials Tech Memo
• Fish and Wildlife Tech Memo
• Endangered Species Act - No Effects Document
• Wetland Discipline Report
• Conceptual Wetland and Watercourse Mitigation Report
• Cultural Resources Report (Section 106) and supporting documents
• 4(f)
• Crime Prevention Through Environmental Design (CPTED)

August 2018

• 1st Ave NE Improvements handout

April 2018

• Spring 2018 Outreach Summary

March 2018

• State Environmental Policy Act (SEPA) checklist
• Mitigated Determination of Non-Significance (MDNS)
• Drop-in session display boards
• Environmental review handout
• Project area mailer

February 2018 - Project information folio

December 2017 - Email update

November 2017

• Presentation to North Seattle College

October 2017 - Email update

August 2017

• August Open House Summary
• Open house postcard
• Open house display boards
• Project fact sheet
• Online open house

July 2017 – Email update

June 2017

• Presentation to Bicycle Advisory Board
• Presentation to Maple Leaf Community Council
• Presentation to Pedestrian Advisory Board

April 2017 – Project fact sheet

Previous Design Materials:

October 2015

• Open house presentation
• Display boards
• Project factsheet
• Event summary

September 2015 – Seattle Design Commission presentation

June 2015 – 2015 TIGER Grant application

July 2015 – Project factsheet

November 2014 - Northgate Pedestrian and Bicycle Bridge: Alternative Development and Selection report

October 2014 – Presentation

September 2014 – Presentation

August 2014 – Presentation

June 2014

• Presentation
• Display boards
• Summary
• Project brochure

April 2014 - TIGER Grant application  (Not selected. TIGER Grant is a highly competitive federal funding source)

April 2014 - Project fact sheet

February 2014 - Presentation

Background Resources

• Northgate Urban Design Framework – July 2013 (Seattle DPD)
• Northgate Pedestrian Bridge Feasibility Study Report – December 2012 (King County Department of Transportation)
• Northgate Outreach – Report on Focus Group Findings – April 2013 (Seattle DPD)
• Seattle Bicycle Advisory Board
• Seattle Bicycle Master Plan
• Seattle Department of Planning and Development - Northgate
• Seattle Neighborhood Street Fund Program
• Seattle Pedestrian Advisory Board
• Sound Transit Northgate Station Project Web Page
• Sound Transit - Transit Oriented Development Urban Design Study