Core Design Team

Firm: VIA – A Perkins Eastman Studio

Alan Hart, AIA
Ashwin Kamath
Justin Panganiban, AICP
Eric Birkhauser, AIA
Mahlon Clements, AIA
Emily Perchlik, AIA
Greg Ball, AIA
Mark Nielson
Jemae Hoffman
Stephia Mulia
Kurniati Kandiawan

Consultants/Collaborators

Structural Engineer: David Evans and Associates
Client Rep Structural: Integrity Structural Engineering
Civil Engineer: CM Design Group
Landscape Architect: Johnson + Southerland
Construction and Cost Estimating: Ott-Sakai & Associates
Public Outreach: Stepherson & Associates Communications
Project Artist: Charles Sowers Studios
Drainage: Osborn Consulting
Electrical Engineer: Joseph Couples Engineering
Environmental: Clearway Environmental
Geotechnical: HWA GeoSciences

Project Narrative

Introduction
The John Lewis Memorial Bridge is a new pedestrian and bicycle bridge that spans Interstate-5 in Seattle’s Northgate neighborhood, linking the newly opened Northgate Light Rail Station and bustling Northgate urban center to the North Seattle College campus, a UW medical satellite campus, and the residential neighborhoods beyond. Building off a prior effort, the project was restarted in 2016 with a new team led by the Seattle Department of Transportation (SDOT).

The team developed a new concept that fit the budget and simplified construction while elevating the design and experiential goals set by the community. The Northgate area of Seattle, long-anchored by the presence of Northgate Mall, has undergone a steady evolution into a more accessible and pedestrian-friendly environment. The John Lewis Memorial Bridge is the culmination of extensive public engagement in addition to progressive planning efforts to continue this evolution. This vital infrastructure connection to expanded light rail service realizes the vision of inclusive mobility, livable growth, and active, accessible transit connections from the east side of the freeway to the west side. The bridge unites communities that have been historically split by the interstate, inspiring the naming of the bridge to be after historic activist and connector of communities, John Lewis.

The design of this 1,900-foot-long bridge is the outcome of a productive and collaborative process between the design team, client, and the community. Significant community engagement produced environmental and aesthetic input that was key to the bridge’s ultimate design and features. More than 10 public involvement events including open houses and drop-in sessions with over 250 attendees, 50+ community briefings, and over 90,000 mailers provided information and updates to the local community who then submitted feedback. The public responded with enthusiasm and influenced the design, particularly in the areas of safety and security, wayfinding and traffic control, environmental elements, and accessibility.

Design
John Lewis Memorial Bridge features varying structural span types to minimize costs. Strong visual continuity across the various span types is achieved with graceful architectural transitions and consistent geometric vocabulary. The Vshaped columns create a fluid visual rhythm and were located carefully to protect the sensitive environment on the west side. The main span over the freeway is achieved with a simple steel Vierendeel truss. To enhance the feeling of openness for users on the bridge, the trusses lean outward at 12 degrees and were designed to avoid the need for lateral bracing, which is unique for bridges of this type. The curving top cord of the truss draws inspiration from the iconic silhouette of Mt. Rainier creating a dramatic feature that serves as a landmark. The bridge was designed for equitable access by all mobilities using a maximum 5% running slope for the main connection path. Horizontal curves meet bicycle requirements to allow ease of access for all types of non-motorized transportation to encourage a more active and healthy community.

The bridge and landings are sited to seamlessly integrate with the College and neighborhood on the west with a direct connection to the light rail station mezzanine level and bicycle network at grade on the east. The bridge and station were designed and constructed in close coordination to allow for a joint grand opening.

Placemaking
The mere presence of the new pedestrian bridge begins to shape the way that people are interacting with the built environment of Northgate. What once required street-level walking/biking under a dark and unsafe freeway overpass, often done with minimal barriers to active traffic, pedestrians can now directly engage with neighborhood amenities whether that’s on their way to work, school, or simply exploring.

The experiential design of the bridge crossing incorporates multiple overlooks enhanced with art, seating, emergency phones, and vantage points for wildlife viewing and urban observation. Overlooks are integrated with areas of interest on the site, creating moments for rest to observe wildlife, urban observation, and learn about the legacy of John Lewis. The path between the College and Transit Center was limited to a maximum 4.7% slope to create the most accessible grade for users of all abilities. Clear sightlines and facial recognition level lighting at night were critical for safety and security and are achieved with integrated handrail lighting and a highly transparent cable netting as a barrier.

The cable net gracefully transitions from a standard guardrail height to the necessary roadway barrier height required when crossing the freeway. This system is inclined to match the open angle of the main span of the truss enhancing
the sense of openness on the bridge. The project Artist worked closely with the design team to select a location and develop a concept that enhanced the experience. The Artist developed a kinetic fin installation that through a series of sensors echoes the movement of bridge goers.

Sustainability
Through the design and construction process, the project had numerous regulatory approvals from the Washington State Department of Transportation, Sound Transit, and the Seattle Design Commission. The Envision checklist was utilized to verify the effectiveness of the project’s sustainable objectives, influencing the materials specifications of the concrete and steel. While conducting lifecycle analysis for the project, the Association of State Highway and Transportation’s Official (AASHTO) code requirement of 75-year design life was exceeded by 25 years.

The project had severe site constraints including spanning a highly-sensitive riparian environment together with a long span over a major freeway and connecting to an active transit station. The project site is in the upper reaches of Thornton Creek, in an urban watershed that drains into Lake Washington. Mitigation was required to address project impacts on fish habitat and riparian functions for a series of connected watercourses, wetlands, and wetland buffers on the North Seattle College campus west of I-5 and for a watercourse on the east side of I-5. A combination of on-site and off-site wetland creation, re-establishment, restoration, and enhancement provided this critical mitigation.

Conclusion
The John Lewis Memorial Bridge creates new, safe routes for people biking, walking, rolling, and taking transit in Northgate. With Sound Transit’s Link light rail now operating at the Northgate Station, people have expanded safe, affordable, and accessible options to travel across the region. After years of planning, design, community engagement, and construction, Seattle can be proud of the connections and opportunities the bridge makes possible. The community focus, elegant design, and streamlined project delivery manifest the equitable development priorities of SDOT, WSDOT, Sound Transit, and the surrounding community together into this elegant and transformative piece of urban infrastructure.