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Aerial view of a long floating bridge spanning a wide body of water with urban areas on both sides.Aerial view of a long floating bridge spanning a wide body of water with urban areas on both sides.

Tolling keeps Washington bridge afloat 

Toll financing enabled the Washington State Department of Transportation (WSDOT) to replace Seattle’s aging SR 520 floating bridge, ensuring safety and multimodal access. 

Client

Washington State DOT

Location

Seattle, Washington

Practices

Toll and Revenue

Markets

State Department of Transportation

Connect with an expert

Sorenson_Tim_2021.jpg
Tim Sorenson PE
Transit & Urban Mobility Practice Leader

Replacing a vulnerable bridge with a toll financing solution

Seattle’s original SR 520 floating bridge—built in the 1960s—had become unsafe, outdated, and inaccessible for pedestrians and bicyclists. WSDOT partnered with CDM Smith to conduct a traffic & revenue study and construction of a new 1.44-mile bridge, the longest floating bridge in the world. 

Forecasting toll revenues accurately  

Revenue experts projected traffic and tolls through 2056, building accurate forecasts to enable bond sales and financing. 

Coordinating across agencies

CDM Smith helped to resolve rate concerns with the state Transportation Commission, advisors, and fiscal consultants. 

Delivering multimodal access

The state's new bridge now includes HOV lanes, transit facilities, and a bike-pedestrian path for safe multimodal travel

Ensuring long-term financial stability  

CDM Smith is providing updated yearly forecasts based on bridge tolling data, changes in toll rates and construction schedules. 

Bolstered by accurate forecasts and strong coordination, WSDOT's new bridge now provides three lanes each way, multimodal access, and resilience against natural hazards. One year after opening, the SR 520 floating bridge received the prestigious Grand Conceptor Award from the American Council of Engineering Companies, cementing its place as a model of modern infrastructure delivery. 

Curious to learn more?

Connect with an expert to learn how we delivered this project.

Sorenson_Tim_2021.jpg

Tim Sorenson

Transit & Urban Mobility Practice Leader

Tim has spent more than 30 years creating sustainable, community-focused transportation solutions integrating mobility, infrastructure, and the environment.

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