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King Street Station Bridge Seismic Projects
Project Description and Location The King Street Bridges are located along heavily traveled arterials situated between two culturally diverse Seattle Downtown Neighborhoods, Pioneer Square and the International District, and immediately adjacent to the City’s intermodal terminal, the King Street Station. The seismic retrofit improvements constructed by the King Street Bridges Project will increase the seismic performance of these bridges in order to meet the City’s objective of maintaining service along these key transportation corridors after a design level earthquake. Collectively referred to as the “King Street Bridges” they are specifically:
Bridge History and Project Objectives The program objectives are to devise, design and construct seismic retrofits for each project to enhance the existing seismic performance of the structures and thereby improving the probability of the structure of maintaining structural reliability, public safety, and traffic mobility after a seismic event. As part of the final design process, consideration will be given to the following factors:
All four bridges were constructed in circa 1911, a time when seismic events were acknowledged but not fully understood nor encapsulated in the design codes for bridges. As a result, structures of this age are not designed to perform or withstand earthquakes that bridges are currently designed for these days. In order to enhance the seismic performance of these four bridges and retain use of key transportation corridors after a post-seismic event, an assessment will be made of the bridge’s seismic vulnerability and seismic retrofit measures will be devised, designed and constructed that will adequately address the seismic deficiencies of the individual structures. Project Schedule The design was completed at the end of 2011 with construction starting in Spring of 2012; because of the complexity of the project and constraints in schedule requirements, the duration of construction is expected to last approximately two year. Almost all of the work anticipated will be done during the night due to conditions regarding access into the project site. It is expected that minimal disruption will be seen by traffic, bicycles, and or pedestrians. Should any work above ground need to be done traffic will be detoured accordingly.
Environmental Considerations SDOT conducted an environmental review of the King Street Bridge Projects and determined the project will not have significant adverse environmental impacts. A State Environmental Policy Act (SEPA) Determination of Nonsignificance is expected to be issued. The environmental review considered potential impacts related to ground disturbance, air and water quality, plants and wildlife, hazardous materials, land use, transportation, and cultural and historic resources, among other things. The project is currently being reviewed as a Categorical Exclusion under the National Environmental Policy Act (NEPA) by the Washington State Department of Transportation and the Federal Highway Administration. SDOT expects to receive approval under NEPA early this year. If you have any questions regarding this process please feel free to contact: Mark Mazzola, SDOT environmental coordinator, at 206-733-9117 or mark.mazzola@seattle.gov. Public Outreach We are working closely throughout the project with local government, institutions, community groups and businesses, as well as transportation agencies and nearby neighbors, to gather information and help ease construction impacts. During construction we plan to continue to provide information about the project to the public and keep neighbors engaged through regular e-mail updates. To join our e-mail list, send an e-mail to maribel.cruz@seattle.gov. Questions or comments? Contact the SDOT Project Team: Kit Loo Maribel Cruz Project Funding
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The project is funded by 
In addition, SDOT proactively sought and secured additional funding for these four bridges through the Federal Highway Bridge Program (HBP). HBP provides funding for the replacement and rehabilitation of deficient bridges and large preventative maintenance projects.
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