Bridges and Roadway Structures
SDOT operates and maintains over 149 bridges throughout Seattle, including four movable bridges.
Three of SDOT's movable bridges are draw bridges, known as bascule bridges. These are the Ballard Bridge, Fremont Bridge and University Bridge. The fourth movable bridge is the Spokane Street Bridge, which is a swing bridge.
For more information on Seattle Bridges and Roadway Structures, call 206-684-8325.
The First Avenue South Bridges, two parallel bridges at the City of Seattle's southern border, and the Montlake Bridge, are movable bridges maintained and operated by the Washington State Department of Transportation. The South Park Bridge is operated by King County.
The State also owns the Alaskan Way Viaduct, the Battery Street Tunnel, and Aurora Bridge, which are part of State Route 99. The City of Seattle performs some maintenance for these structures on SR99 under an agreement with the State. In addition to the bridges listed above, these are various viaducts that are part of Interstate 5, owned and operated by Washington State, and there are railroad bridges owned and operated by Burlington Northern Railroad.
Seattle Bridges Operated by SDOT:
The Ballard Bridge, located at the west end of the Lake Washington Ship Canal at Salmon Bay, is the fourth and last of the Lake Washington Ship Canal Bridges to be passed before entering Puget Sound from Lake Washington. Built in 1917 with a length of 2,854 feet, the Ballard Bridge links the Magnolia and Queen Anne neighborhoods with Ballard.
The Fremont Bridge, located west of the George Washington (Aurora) Bridge, crosses the Lake Washington Ship Canal and links the Fremont with the Queen Anne neighborhood. Opened on July 4, 1917, it is the only blue and orange bridge operated by SDOT. The Fremont Bridge's current color was chosen by a 1985 poll taken among Fremont residents and by the Fremont Arts Council.
The Fremont Bridge celebrated over 566,000 openings and counting as of January 2006. Just 30 feet above the water, the bridge rises for marine traffic on average of about 35 times a day, making it as one of the busiest bascule bridges in the world.
Southwest Spokane Street Swing Bridge
The Southwest Spokane Street Swing Bridge spans the Duwamish River, and links South and Southwest Industrial Seattle with Harbor Island, a major shipping and ship building area. Completed in 1991, it is the world's first and only hydraulically-operated concrete double-leaf swing bridge. Each of the bridge's 480 foot leaves weigh 7500 tons.
The Southwest Spokane Street Swing Bridge is the last in a series of bridges that has spanned the Duwamish River. The bridge's predecessor did not provide commercial boat traffic adequate room to maneuver past the bridge. By constructing a swing bridge, the City of Seattle widened the channel for boat traffic, while also cutting operating and construction costs.
SDOT has been awarded several prestigious awards for the design, construction, maintenance and operation of the Southwest Spokane Street Swing Bridge, including:
1991 - Outstanding Engineering Achievement Award by the Washington State Society of Professional Engineers.
1992 - Grand Award for Engineering Excellence by the American Consulting Engineers Council.
1992 - Grand Award for Excellence in Concrete Construction by the Washington Aggregates and Concrete Association.
1992 - Outstanding Engineering Achievement Award by the National Society of Professional Engineers.
1992 - Outstanding Engineering Achievement Award by the American Society of Civil Engineers.
1992 - Award of Excellence by the Portland Cement Foundation.
1995 - Design of Transportation Honor Award by the National Endowment for the Arts.
The University Bridge spans Portage Bay, linking the University District with the Eastlake and Capitol Hill communities. It is the second of the four Lake Washington Ship Canal Bridges. The University Bridge was originally built in 1919 and remodeled in 1933. President Franklin D. Roosevelt dedicated the bridge on April 7, 1933. On that opening day, 37,794 automobiles crossed the bridge. The addition of the I-5 bridge has decreased traffic over the University Bridge in recent years. A 1983 traffic count recorded 27,735 vehicles using the bridge daily.