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Bridges

Hood Canal Bridge at sunset
The Hood Canal Bridge on SR 104
between Kitsap, and Jefferson counties
providing a link to the Olympic Peninsula.

Washington bridges are critical transportation links whether you travel on a two-lane overpass, or a huge double-decker bridge carrying hundreds of thousands of cars a day. There are roughly 7,000 bridges and structures on the state, city and county road systems and WSDOT is responsible for managing an inventory of nearly 3,500 of these critical transportation links.

Bridge Safety
The safety of bridge structures in Washington State is ensured through a meticulous inspection system, incorporating state and local agency inspection contributions. The condition of all bridge decks, superstructures and substructures are rated based on these inspections.

Tacoma Narrows Bridge
The Tacoma Narrows bridge on SR 16
between Tacoma and Gig Harbor

Inspections
Most bridges are inspected every two years, with a few exceptions. Some bridges with structural issues and older bridges are inspected more frequently. The Alaskan Way Viaduct in Seattle, for example, is inspected thoroughly every six months. 

With the past collapse and replacement of the I-35W bridge in Minnesota, much of the national discussion has focused on bridge safety and structural classification ratings. Unfortunately, these discussions have led to much confusion as to the actual meaning of the terms.

The Federal Highway Administration (FHWA) requires all state transportation agencies to report state, city, and county Structurally Deficient (pdf 240 kb ) and Functionally Obsolete bridge ratings each year. These ratings are used to help determine federal bridge replacement and rehabilitation funding levels to the states.

I-90 Vantage bridge

The Interstate 90 Bridge over the
Columbia River at Vantage

A study performed by the Federal Emergency Management Agency in 2001 found that Washington has the second highest risk for economic loss in the nation due to earthquakes. California has the highest risk. The largest earthquakes in recent history in Washington occurred in 1949, 1965 and 2001 and killed 15 people. The most recent Nisqually earthquake killed one, injured 320 and caused over $2 billion dollars worth of damage.

WSDOT has an aggressive seismic retrofit program with clear goals of minimizing loss of life and disruption of commerce, as well as reducing the risks of complete bridge collapse.

SR 504 Bridge
Crews clearing snow from the Hoffstadt Creek Bridge on SR 504

National Leader
WSDOT is a national leader in its approach to inspecting and maintaining its bridges and structures. Our bridge engineers are regularly asked to participate and contribute expertise to national committees shaping and developing future innovations in bridge engineering.

WSDOT’s Bridge Program emphasizes the importance of cost effective preservation programs, such as bridge replacement and rehabilitation, seismic retrofit, bridge painting, bridge deck rehabilitation, and bridge foundation scour mitigation.