Bridges

What we do

Some of Seattle's bridges make connections over bodies of water, like the West Seattle Bridge. Other bridges, like the Magnolia Bridge, are viaducts that make connections over valleys. Some bridges, like the Fremont Bridge, serve all travel modes and others are limited to foot or bike traffic, like the W Thomas St Overpass.

SDOT owns, inspects, maintains, and/or operates nearly 280 bridges. Bridge program work includes:

• Bridge Painting Program: Painting steel and other metal on bridges protects them from corrosion and rust. The typical life of bridge paint is 18 years.
• Bridge Load Rating Program: Managing the safe weight capacity of bridges is an important element to bridge safety. Activities include analysis of the weight capacity of bridges, field verification tests, and monitoring of instrumentation on deficient bridges.
• Capital Improvement Program: Some bridges require major  rehabilitationor replacement to ensure they remain safe and available to the traveling public. Capital projects often involve a multi-year planning, design, and engineering process.

This Capital Projects and Roadway Structures 2018 Annual Report provides information about SDOT's key structural assets: bridges, retaining wall, stairways and areaways.  Combined, these assets represent over $8.3 billion in replacement value. The report also highlights capital improvement projects that were completed or underway in 2018. 

Bridge openings

In the city, there are7 vehicular moveable bridges over navigable water, of which 4 are owned by SDOT. Federal law requires bridges open for marine traffic, with few exceptions. Seattle is part of the US Coast Guard 13th District. More information is available at www.uscg.mil/d13/.

Seattle's moveable bridges

Here is a list of vehicular bridges in Seattle that open for marine traffic.

Bridge opening schedule

Bridges open on request between 7 AM and 11 PM. From 11 PM to 7 AM, bridges open by appointment only. The average bridge opening, from the time street traffic stops to the time it resumes, lasts about 4 minutes. The Spokane St Swing Bridge openings last about 10 minutes.

Seattle's Ship Canal Bridges - University, Fremont, and Ballard Bridges - have restrictions in place during the morning and afternoon peak commute to help keep street traffic moving during busy hours. These 3 bridges stay closed to marine traffic on weekdays, from 7-9 AM and from 4-6 PM, except for federal holidays but Columbus Day and for any vessel of 1,000 gross tons or over. See the federal regulation for Lake Washington Ship Canal bridges here. Information on Montlake Bridge openings is available here.

How to request a bridge opening

· Between 7 AM and 11 PM, vessels should contact the bridge by radio (Marine Channel 13 or call (206) 386-4251) or use a whistle signal: one long, one short.

· The US Coast Guard requests pleasure vessel use a whistle signal from 7 AM to dusk.

· Between 11 PM and 7 AM, bridge openings are by appointment only, and should be requested no less than 1 hour prior to the opening.

· For openings by appointment, the bridge operator will wait 15 minutes after the appointment time before contacting the vessel on Marine Channel 13. If the bridge operator doesn't receive a response, the operator will leave for the next appointment. · For state- or county-owned bridges, visit www.kingcounty.gov/ or www.wsdot.wa.gov.

Vehicle weight restrictions on bridges