Recent guest columns about state Route 520 [published] in the Madison Park Times appeared to mix-and-match bridge dimensions and mischaracterized traffic growth and wetlands effects. We would like to set the record straight on these topics.

Floating bridge height and width — To be clear, the new floating bridge will be about 116 feet wide and about 20 feet above the water, both measurements at midspan.

Floating bridge expanded for light rail — If, in the future, the region votes to fund light rail on the SR 520 corridor, the new floating bridge could measure 150 feet wide to include space for light-rail trains. Graphics of the bridge in this configuration are on our website:

West of the floating bridge — The current bridges and ramps west of the floating bridge are 150 feet wide. When the new bridge is built in that area, it will be two structures, totaling 160 feet to 262 feet wide, to accommodate on- and off-ramps and a gap for future light rail.

Traffic growth — The second guest column (“Flawed Assumptions, Lingering Questions in SR 520 Bridge Construction,” September 2011) cited a downward trend in traffic on SR 520, claimed by a group called Sightline Daily. 

As we discussed in other local media, its analysis didn’t capture a complete picture of traffic on the corridor. Its analysis starts in 1996, the peak year of growth and traffic over the last 25 years, and continued through 2010, capturing the dot-com bust between 2000 and 2003 and the subsequent national recession, both with significant traffic effects in this region.

In contrast, the Washington State Department of Transportation’s (WSDOT) longer view of traffic data on the SR 520 bridge begins in 1984 and projects to the year 2030, capturing nearly 30 years of historical data to produce a more accurate trend. Traffic generally rose annually since 1984, until the beginning of economic uncertainty in the middle of the 2000s. 

The column also wrongly says 113,000 cars currently cross the bridge weekly; our final EIS analysis shows that 115,000 cars cross the bridge daily.

Thorough analysis — The second guest column also said WSDOT has moved too quickly, finalizing the environmental[-impact] process without answering questions from the community. 

WSDOT began its comprehensive analysis of SR 520 bridge replacement in 1997. Since then, WSDOT provided information at more than 500 public events, including open houses, community design workshops and briefings, fairs and festivals. 

We regularly e-mail more than 5,000 individuals. We’ve responded to more than 5,000 comments and questions from the public and agencies since 2003. We’ve reached more than 36,000 people at fairs and festivals and other events. 

WSDOT analyzed more than 30 options before selecting the preferred design, including lane configurations, bridge types, tubes and tunnels. 

We also completed nine state and federally required documents, each with full environmental and traffic analysis. [These are] available on the SR 520 website (

Wetlands in Union Bay — Most of the wetlands in Union Bay were created when the locks were constructed and Lake Washington was lowered roughly 9 feet in 1917, not due to activities by beavers. 

WSDOT recognizes the importance of wetlands in our natural areas, and we try our best to avoid or minimize any project effects to natural resources. For effects we cannot avoid or minimize, we propose mitigation projects. 

WSDOT is committed to its policy of “no net loss” of wetlands, and we have proposed several wetlands-mitigation projects around the project area, including more than 9 acres of mitigation at the WSDOT Peninsula and the Washington Park Arboretum. You can view a complete list of wetland mitigation projects on-line ( 

Thank you for the opportunity to share details about our efforts. The Washington State Department of Transportation has invested years comprehensively analyzing designs and effects of improving SR 520, and it continues to work with the community. 

After 14 years of work, construction is under way on mobility and safety improvements. Many details are on our website at

— Jeff Switzer, communications officer 

WSDOT’s SR 520 Bridge Replacement and HOV Program