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Seattle Bridges
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State-Owned Bridges

Bridges and Roadway Structures
Bridge Openings

The City of Seattle operates three bascule bridges over the Lake Washington Ship Canal and two bridges over the Duwamish River—one  swing bridge and one bascule bridge. The openings and closings of these bridges have a major impact on the lives of commuters and boaters.

SDOT wants the use of these bridges to be as easy and convenient as possible. The following information answers frequently asked questions about the bridges, and should help ease the way for both commuters and boaters on their respective routes.

For more information about Seattle Bridges and Roadway Structures, call 206-386-4208.

Bridge Opening Procedure

When requesting a bridge opening from 7:00 AM - 11:00 PM vessels should contact the bridge by radio (marine Band ch 13) or use a whistle signal - one long, one short. Pleasure vessels are requested by the Coast Guard to use a whistle signal from 7:00 AM to dusk. Boaters please see the Rush Hour Schedule below, as bridge openings are restricted during these time periods. For bridge openings after 11:00 PM to 7:00 AM, please see section below titled Bridge Openings by Appointment.

Average Time of Bridge Openings

On the Lake Washington Ship Canal, a bridge opening averages about four (4) minutes, from stopping traffic to letting traffic resume at the end of an opening. Openings of the Spokane Street Swing Bridge average about 10 minutes in length. SDOT appreciates that delays are an inconvenience -- we get stuck in them too!

Vessel Clearances

(See Footnote 1)

Ballard Bridge - 44'

Fremont Bridge - 30'

University Bridge - 42', 6"

Montlake Bridge - 46'

Spokane Street Swing Bridge (See Footnote 2) - 55'

Footnote 1 - For center portion of bridge at mean regulated lake level

Footnote 2 - At mean high water

Federal Rules and Regulations

Federal law gives marine traffic the right-of-way over vehicular traffic. The City of Seattle must apply to the U.S. Coast Guard for exceptions to that rule. The exception for bridge closures during rush-hour periods is granted by the Coast Guard. The Coast Guard also allows vessels to be held for 10 minutes on the Lake Washington Ship Canal bridges to allow accumulated vehicular traffic to clear.

For more information about the rules and regulations of bridge operations, please refer to the code of Federal Regulations, Title 33. These books are available at the U.S. Government Book Store in the Federal Building, or at your local library. The WWW version of Title 33, Navigation and Navigable Waters, is available at this URL:

During the year, the City requests the Coast Guard to approve temporary changes in operation of the bridges. These temporary changes are published in the U.S. Coast Guard's Local Notice to Mariners. This is a free publication. The WWW, adobe and gopher versions of this document are available at this URL:

The 13th Coast Guard District, located here in Seattle, has a home page at:

South Park Bridge

SDOT operates the South Park Bridge under a contract for King County. 206-549-2896

Southwest Spokane Street Swing Bridge (Low-Level)

The Southwest Spokane Street Swing Bridge opens on demand, even during rush hour. Commuters should be aware that marine traffic may go through the bridge at any time.

Flashing signs on the various approach roadways warn commuters that the low-level bridge is open for marine traffic and closed to vehicular traffic. Commuters can then use the West Seattle High-Rise Bridge.

Vessels should contact the bridge by radio or whistle signal when requesting an opening. Pleasure vessels are requested to use whistle signals as primary contact from 7 a.m. to dusk.

Lake Washington Ship Canal Bridges

Rush-Hour Schedules

To keep roadway traffic moving during peak driving times, bridge openings are restricted.

Ballard and Fremont bridges remain closed to boaters weekdays from 7:00 to 9:00 a.m. and 4:00 to 6:00 p.m., except national holidays. (See Footnote 1 below.) The University bridge remains closed to boaters weekdays from 7:00 to 9:00 a.m. and 4:00 to 6:00 p.m., except national holidays.

During closed periods, bridge openings will not be made unless a vessel is 1,000 gross tons or more, or is towing a vessel exceeding 1,000 gross tons (Federal Regulation).

Footnote 1 - Closed periods will be in effect for the Columbus Day holiday.

Bridge Openings by Appointment

One bridge operator (the Call-out Bridge Operator) is responsible for the three Ship Canal bridges between 11:00 p.m. and 7:00 a.m. Vessels are required to give one hour advance notice for a bridge opening. To request an opening, vessels should call the Bridge Shop on Marine Channel 13, or by telephone at 386-4251 after 11:00 p.m. The operator will drive to the bridge at the agreed time.

The signal for all Lake Washington Ship Canal bridges is one prolonged then one short whistle blast.

If the vessel is not there, the operator will wait 15 minutes and then try to contact the vessel using Marine Channel 13. If there is no response, the operator will leave the bridge and go to the next appointment.

The Call-out Operator schedules all the appointments for efficient use of time by grouping boats and limiting the amount of driving time between bridges.

Opening Information for State and County Bridges:

Washington State Department of Transportation (WSDOT) owns and operates these bridges:

(Call the phone number provided below for info about that bridge's openings.)

First Avenue South Bridges - 206-764-4160

SR 520 Floating Bridge - 2 hour notice, with the exception of M-F 6:30am-10 a.m.& 3 p.m. – 7p.m. excluding Federal holidays - 206-440-4490

Hood Canal Bridge - 1 hour notice - 360-779-3233

Montlake Bridge - 206--720-3048

WSDOT 24 hour phone - 206-440-4490

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