COVID-19
For the latest COVID-19 health guidance, statistics and resources, visit Coronavirus.wa.gov.
When the original, four-lane SR 520 floating bridge across Lake Washington opened in 1963, fewer than 1 million people lived in King County, and Bellevue, the Eastside’s largest community, had only about 13,000 residents. Since then, the county’s population has more than doubled, while Bellevue’s has swelled tenfold. And the area’s robust growth continues: The Puget Sound Regional Council predicts the Central Puget Sound region will add 1.2 million more workers and another 1.8 million residents by 2050.
Traffic congestion on an old, unimproved stretch of SR 520.
The region’s growth has long overtaxed SR 520’s six-decade-old design. Prior to the start of the highway’s reconstruction, vehicle speeds during peak commute times routinely averaged below 20 mph.
In addition to replacing aging bridges at risk of failure in a severe earthquake or windstorm, the SR 520 Bridge Replacement and HOV Program is making significant improvements to the SR 520 corridor that will enhance the public’s transportation options and mobility for generations to come. Many of these enhancements are now complete, while others are fully funded for construction in the coming years.
We are constructing new, multimodal highway features that provide greater mobility options for all users, including drivers, transit riders, bicyclists, and pedestrians.
Riders board a Seattle-bound bus from SR 520's new Evergreen Point transit station in Medina.
When SR 520 is fully built out, the highway’s corridor improvements will give the public:
The improved SR 520 corridor will enhance highway safety, reduce congestion and lower travel times for bus riders, carpoolers and drivers. According to traffic studies (pdf 13.9 mb), the regional benefits of SR 520 reconstruction will include:
When fully built out, SR 520 will have transit/HOV lanes along its entire length, from Redmond to I-5. Shown here is a stretch of the Eastside’s reconstructed corridor.
To help meet rising travel demand between the Eastside’s growing cities and Seattle’s booming South Lake Union area, we plan to construct a reversible transit/HOV connection between SR 520 and the I-5 express lanes, with direct access to Mercer Street. We expect this new connection to open as early as 2023 for transit. The connection will open to carpools after a new Portage Bay Bridge and Roanoke lid are completed, in approximately 2029.
Learn more on our SR 520/I-5 Express Lanes Connection Project webpage.
A bus stops at the Evergreen Point median transit station in Medina before crossing the new SR 520 floating bridge.
We opened major transit improvements on SR 520’s Eastside segment in 2014. Two years later, we further enhanced the corridor’s transit operations when we opened the new, six-lane floating bridge on Lake Washington. These improvements are prioritizing bus trips, reducing unsafe merges, and providing a more reliable trip for transit riders between the Eastside and Seattle.
The Eastside’s new transit infrastructure includes:
The new six-lane floating bridge, unlike its four-lane predecessor, also has transit/HOV lanes operating in both directions.
(Note: During Montlake Project construction, we are removing the old, 1960s-era west approach bridge over Union Bay and building a new bridge for eastbound traffic, parallel to the westbound bridge that opened in 2017. During this time, all traffic between Montlake and the floating bridge travels on the new westbound bridge, with two general-purpose lanes in each direction, and no transit/HOV lanes.)
Although there currently are no proposals or funding to build light rail across SR 520, WSDOT engineers designed the new SR 520 floating bridge so that additional supplemental pontoons could be added in the future to support the weight of light rail. As shown in the graphics below, the bridge could accommodate light rail either by converting the bridge's transit/HOV lanes to light rail, or by adding more width.
Adding light rail to the SR 520 floating bridge would require analysis of transit connections and routes, additional funding, regional decision-making, and a separate environmental review process. WSDOT estimates a cost of $150 million to $200 million to construct and install the 30 additional pontoons needed to support light rail. There would be additional costs associated with the bridge-deck expansion and other infrastructure, including rail lines.
The current SR 520 floating bridge
With two general-purpose lanes and one transit/HOV lane in each direction.
Scenario 1: With light rail displacing the transit/HOV lanes
Scenario 2: With light rail in addition to the transit/HOV lanes