Northgate Ped/Bike Bridge construction update

Late July daytime bridge span work over 1st Ave NE (between NE 100th St and NE 103rd St)

The week of July 20-24, crews will be installing the first set of spans on 1st Ave NE. The spans included in this work make up the portion of the bridge that’s commonly referred to as the “hairpin turn.”  

Work hours are from 10 AM to 7 PM and require trucks transporting equipment, a large crane for installation, and a single lane closure of 1st Ave NE. Northbound and southbound travel will be maintained. 

East side of I-5 (1st Ave NE between NE 100th St and NE 103rd St)

• Ongoing intermittent lane closures between 7 AM and 3:30 PM, with northbound and southbound traffic maintained
• Sidewalk demolition
• Structural excavation
• Streetlight wiring and foundation installation
• Ongoing concrete work for several pier columns:
  • Placing forms and rebar cages (see photo below)
  • Placing concrete
  • Allowing concrete curing time
  • Removing the forms

Placing forms and rebar cages on the east side of I-5. 

Northbound I-5 express lane

Work on the I-5 median, near the northbound I-5 express lane off-ramp at 1st Ave NE and NE 103rd St, will continue later this summer.

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

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

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 sightlines
• 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  

What to expect during construction

• Some noise and construction vehicle activity, including cranes
• Some nighttime and weekend work
• Detours for people walking and biking
• Lane reductions on Northgate express lane on- and off-ramp
• 2 freeway closures and detours (on weekends and at night only)
• Construction staging and parking impacts near the construction sites, including at the northern side of North Seattle College along N 100th St and on NE 100th St at 1st Ave NE
• Closure of the North Seattle Park & Ride on 1st Ave NE

Questions during construction? Contact us:

Darrell Bulmer   Communications and Outreach Lead Northgate Bridge Construction Project NorthgateBridge@seattle.gov (206) 905-3620 www.seattle.gov/transportation/NorthgatePedBridge.htm If you need this information translated, please call (206) 905-3620. Si necesita traducir esta información al español, llame al (206) 905-3620. 如果您需要此信息翻譯成中文 請致電 (206) 905-3620. Kung kailangan mo ang impormasyon na ito na nakasalin sa Tagalog mangyari lamang na tumawag sa(206) 905-3620. اذا تريد ترجمة هذه المعلومات, يرجى الاتصال برقم (206) 905-3620.