East Link is a planned eastern extension of the Sound TransitLink Light Rail system, spanning about 22 miles from Downtown Seattle to the city of Redmond. Funding for construction of the portion of East Link between Downtown Seattle and Overlake Transit Center was approved by voters in November 2008, while the final segment between Overlake Transit Center and Downtown Redmond was identified as a priority extension in a future expansion measure. As of early 2012, construction of East Link was projected to begin in 2015, with the line opening for service as far as Overlake in 2023.
On April 25, 2013, the Sound Transit board decided on a final route for East link,  which will go from the International District/Chinatown Station in Seattle across Lake Washington and Mercer Island, through Bellevue and over Interstate 405 to Overlake Transit Center in Redmond. Voters in Bellevue, Washington approved the Link light rail extension from Seattle, across Lake Washington on Interstate 90, through Bellevue and on to the Overlake Transit Center in Redmond.The project is currently in the final design phase, with construction scheduled to begin in 2015 and service expected to start in 2023. An estimated 50,000 passengers will use East Link every day by 2030.
When the light rail line is completed, it will be the first time that a light rail line has operated on a floating bridge. Challenges faced by Sound Transit include stray current, expansion and contraction of the bridge itself, weight of the rail infrastructure (rails, catenary, etc.), weight of the light rail vehicles, and the expansion joint on either end of the bridge.