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For more information about Seattle Bridges and Roadway Structures, call 206-684-8325.

Below is SDOT’s Bridge Sufficiency Rating list from December 2012.  As the rating is a comparison between the bridge’s condition today and the condition when it was built, it does not have a direct relationship to bridge safety.  (For example, potholes on a bridge’s driving surface would mean a deduction in the rating but no safety impacts.) 

Safety is our number one concern in managing these structures and all of the City of Seattle’s bridges are safe for use.  The Seattle Department of Transportation would close any bridge if we determined the bridge was not safe.   

Post-Earthquake Bridge Inspection - March 6, 2001

They might have hoped not to have to use their emergency plan, but when the earthquake hit Seattle last Wednesday morning, 13 self-starting Seattle Transportation bridge inspection teams went into high gear and began implementing the training and preparation they had for just such a situation. Now that the dust is starting to settle, literally, some of the team members have been available to provide more information about the Post Earthquake Bridge Inspection plan.

The plan, based on lessons learned from earthquakes in Kobe, Japan, Loma Prieta and Northridge in California, mobilizes inspection teams comprised of City and consultant engineers immediately following an earthquake to assess possible damage to the key "life line" bridges. Acknowledging that field mobilization is critical, the plan is self-starting based on the temblor's size, magnitude 5.7 or greater, and centered within 50 miles of the City. The teams pick up packs of radio equipment, bridge details, maps, food supplies for up to three days that are cached in five locations critical to the main bodies of water that divide Seattle - the Ship Canal and the Duwamish Waterway.

John Buswell, one of the creators of the Seattle Bridge Inspection plan, discussed all the details of the inspection plan Tuesday, March 6th, at 10 a.m. at the Lower Level Spokane Street Swing Bridge. Here is some of the background information on the emergency plan.

Response Goal: Inspect key bridges on "life line" routes immediately following earthquake (of magnitude 5.7 within 50 miles of Seattle) to provide accurate information so that all commuters and other City agencies (Fire, SPU, etc) responding to emergencies can plan safe routes to travel.

Response plan designed specifically for Seattle by John Buswell of Roadway Structures, from lessons learned in the California Loma Prieta (SF) and Northridge, California and Kobe, Japan earthquakes.

17 Seattle teams of two inspectors each - comprised of City and consultant engineers.

Teams trained to assess specific bridges.


Earthquake happens:

Self starting: Team members immediately go to one of five locations within the City to pick up emergency response packs of bridge details, equipment, information, radios, food etc.

Packs are located at five key locations in the event bridges go down at the Ship Canal:

2 - north side of Ship Canal
2 - south side of Ship Canal
1 - West Seattle

Team members wait and if partner doesn't show they go on to bridge site alone.

Inspect bridge and radio details to the Emergency Operations Center Bridge Condition Manager.

Bridge Condition Manager conveys info to agencies responding to emergencies.

UBIT: Under Bridge Inspection Trucks

UBIT Facts:

  • The City of Seattle is one of only three public agencies that own UBITs (Under Bridge Inspection Trucks) in the State of Washington. The City of Spokane and the Washington State Department of Transportation are the other two.

    Photo: UBIT in operation at Southwest Spokane Street Swing Bridge
  • The West Seattle Bridge is over 150 feet high and without the UBIT, the City would not have a means for reaching difficult areas to inspect and perform necessary repairs.

  • The City has twenty bridges that require the UBIT for inspection and repair access.

  • The City rents the use of the UBIT to other cities and counties when we are not using it ourselves.

    Photo: UBIT in operation at Southwest Spokane Street Swing Bridge
  • The UBIT the City owns was manufactured by Reach All, a company located in Minnesota.

  • The UBIT can reach 51' 9" under a bridge.

  • The UBIT can reach 63' below the bridge deck.

    Photo: UBIT in operation at Southwest Spokane Street Swing Bridge
  • With three separate booms that pivot, two separate turntables and a bucket that swivels up and down, the operators must be careful not to turn themselves into a pretzel. In fact, the operators can put the combination of booms and turn tables in a position that will not allow the bucket to move. This is a built-in safety feature that assures the UBIT is always balanced and in a safe position.

For more information about the UBIT, contact the division at 206-684-8325.

SDOT Archive: Bridges in the 1993-2000 Seismic Retrofit Program

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