WSDOT announces preferred alternative for SR 520 floating bridge project

Last week WSDOT announced the preferred alternative for the 520 bridge. This is one of the magic steps in the 520 design/contruuction process and is a major milestone. It’s not perfect, but it’s vastly better than no bridge at all. In general I’m pleased with it – we get most of what we wanted.

I’ve attached their press release with some of the major features listed. For lots and lots more information you can visit the website

The remaining task is to identify the funding for the last part of it. I would expect that this will include some revenue from tolling the I-90 bridge as we get further into the construction. Tolls on 520 will turn I-90 into a parking lot without a balanced tolling approach. We have to consider the lake crossing as a single corridor. I’m not excited about tolls, but don’t see a way to avoid them as we try to get a new bridge built.

WSDOT announces preferred alternative for SR 520 floating bridge project

Accommodates future light rail; creates urban interchange with two new blocks of open space at Montlake

 SEATTLE – Washington State Department of Transportation today announced a preferred alternative for how State Route 520 will be rebuilt, marking a major milestone in the environmental review process.

The preferred alternative designates that the aging and seismically vulnerable floating bridge and the Seattle side of the corridor will be rebuilt with two new lanes for carpools and buses in addition to four general purpose lanes. It will also include a new urban interchange at Montlake that reconnects the adjacent Seattle neighborhoods.  The new bridge will be ready for light rail.

This preferred alternative was developed based on public and agency comments received on the supplemental draft environmental impact statement.

“For more than a decade we’ve worked with the neighborhoods, local governments, transit agencies and the public to replace this aging bridge. Today, after all of that hard work and cooperation, we have a new 520 and are ready to move forward to open the bridge in 2014,” Gov. Chris Gregoire said. “We have a bridge that will serve the mobility needs of our region today with new carpool and transit lanes and will be ready for light rail in the future.”

The preferred alternative for the floating bridge and Seattle interchange includes:

  • Four general purpose lanes and two new lanes dedicated to transit and carpools
  • An urban interchange at Montlake Boulevard, with an extended lid to maximize open space and pedestrian/bicycle connections
  • A second bridge and dedicated transit/carpool lanes across the Montlake Cut
  • A path for bicyclists and pedestrians across the lake on the north side of the floating bridge
  • Investments to treat stormwater and reduce traffic noise

“Today’s announcement is a major milestone for the SR 520 project, particularly for those neighbors, community leaders, elected officials and interest groups that have worked with us to develop a vision that provides mobility and reconnects Seattle neighborhoods,” Transportation Secretary Paula Hammond said. “We look forward to working with the City of Seattle, Sound Transit, King County and the University of Washington to finalize design and construction plans.”

In response to neighborhood, city and agency comments, WSDOT designed the preferred alternative to:

  • Lower the floating bridge to approximately 20 feet above the water in the middle of the lake.
  • Be ready for a future light rail connection to Sound Transit’s U-LINK station by creating a space between the bridge structures at the west end of the floating bridge.
  • Reduce impacts to the Arboretum by providing access to Lake Washington Blvd. at 24th Avenue East, eliminating the need for new ramps. Access through the Arboretum will be managed to reduce traffic volumes.
  • Maintain transit priority using direct-access transit/carpool ramps with priority lanes on Montlake Boulevard.
  • Narrow the Portage Bay Bridge to 105 feet, compared to 154 feet as previously proposed.

Plan the Portage Bay Bridge as a boulevard, with a 6-foot-wide landscaped median, and operate at 45 miles per hour to reduce noise effects on the adjacent neighborhoods.

The announcement of a preferred alternative marks a milestone 13 years in the making. Since 1997, WSDOT and regional leaders analyzed design alternatives for a replacement SR 520 bridge and improved corridor. A draft environmental impact statement (EIS) released in 2006 drew more than 1,700 public comments. New designs were drafted and analyzed through a mediation process, and in January 2010 WSDOT released a supplemental draft EIS, which received more than 400 additional comments.

With the decision on a preferred alternative, WSDOT will finalize mitigation plans to address environmental and construction effects. A final EIS is scheduled for completion at the end of the year.

The legislature set the SR 520 program budget at $4.65 billion for improvements from I-5 in Seattle to SR 202 in Redmond. WSDOT continues to analyze the estimated cost of the preferred alternative for the floating bridge and Seattle interchange. The cost is expected to be within the budget set by the Legislature. Toll revenue and state and federal funds provide about $2.37 billion in funding for a replacement six-lane floating bridge and SR 520 improvements on the Eastside.

More information about the SR 520 Program and preferred alternative is available at

Author: Ross

I am the Director of the Department of Early Learning for Washington State. I formerly represented the 48th Legislative District in the State House of Representatives, chairing the Appropriations committee and spent many a year at Microsoft.