On the land bridge, a bermed pathway screens views and sound from the highway, offering a quiet, immersive route across the interchange. Plantings include Douglas iris, Oregon grape, salal, native ferns, and grasses—species chosen for their adaptability, habitat value, and low irrigation needs.
SR 520 Montlake Lid and Land Bridge
Owner
Washington State Department of Transportation
Prime Consultant: HDR Engineering (Structural and Civil Engineering, Landscape Architecture)
Construction Manager: KBA
Design-Build Contractor: Interwest Construction Inc.
Mechanical Engineering: Tres West Engineers, Inc.
Electrical Engineering: Stantec
Landscape Architecture: Parametrix
Lighting Design: Horton Lees Brogden Lighting Design, Stantec
Traffic Consultant: Parsons Brinckerhoff
Artist: Norie Sato
Project Size
Gross area: 24.00 acres
Project Status
In Progress
Services
Urban Design
The SR 520 Lid and Land Bridge project in Seattle’s Montlake neighborhood transforms a major transportation interchange into a vibrant civic asset. Visitors will experience new green spaces, bike and pedestrian connections, and integrated transit infrastructure that reconnect neighborhoods long divided by the highway. Elevated parkland and landscaped berms reduce noise and air impacts, while a network of HOV lanes, transit stops, and future light rail readiness ensures mobility for all.
The design restores the Olmsted Brothers’ original 1903 vision for Seattle’s parks, linking the Washington Park Arboretum and Lake Washington Boulevard with continuous trails and overlooks offering sweeping views. Native plantings and green walls enhance ecological performance, and advanced stormwater systems protect Union Bay and the Lake Washington watershed. As the first phase of a broader corridor transformation, the project reclaims infrastructure as public space, promoting transit equity, environmental health, and community connection.
Photography: Adam Hunter
Along the walls of the lid and land bridge facing the highway, a series of integrated ledges are designed to welcome the growth of moss and ferns over time, eventually becoming green walls that will mimic the charm of mossy, weathered concrete walls in Seattle’s Olmsted parks.
