WSDOT requests proposals for SR 520 floating bridge

“Seeking proposals is an important step toward our goal – replacing this vulnerable bridge so we can continue to serve commuters and commerce every day,” state Transportation Secretary Paula Hammond said. “We expect these world-class teams to show how they will design and build a new floating bridge that meets our schedule and budget.”


WSDOT is breaking ground in Grays Harbor next spring to build 33 emergency replacement pontoons that could also be used for the planned replacement of the floating bridge, Hammond said. “Our momentum is building toward making crucial improvements in the SR 520 corridor,” she said.


The contract for a new floating bridge will include:

  • Building a new six-lane floating bridge with transit/HOV lanes and a bicycle/pedestrian path.
  • Construction of 44 supplemental pontoons and 58 anchors.
  • Use of 33 pontoons to be constructed beginning next year in Grays Harbor as part of a $367 million contract with Kiewit-General Joint Venture.
  • Building facilities to treat stormwater from the roadway before it reaches Lake Washington.
  • Building an east approach connection and a new maintenance facility and dock on the east shore of Lake Washington.


This is the third design-build project for the SR 520 corridor program in the past year. Design-build is a type of contract that combines project design and construction into a single contract. A designer and contractor join forces to submit a detailed design and construction proposal with a fixed price.


WSDOT began a thorough environmental analysis of the project in 2000. The draft and supplemental environmental analyses published in 2006 and 2010 show that, when completed from I-5 to Medina, the floating bridge project will improve travel times and reliability in the corridor. The new SR 520 also will meet current design and safety standards. The environmental review of the I-5 to Medina Bridge Replacement and HOV Project, which includes the floating bridge project, is scheduled to be complete in 2011.


The floating bridge project is funded in part by toll revenue to be collected on the floating bridge starting spring 2011. The legislature set the SR 520 program budget at $4.65 billion for improvements from I-5 in Seattle to SR 202 in Redmond. Toll revenue and state and federal funds provide about $2.37 billion in funding for the SR 520 improvements. WSDOT will continue working with the state Legislature to identify additional funding for other improvements in the corridor.


More information about the SR 520 Program is available at