From WSDOT: 

Based on a joint agreement between WSDOT, King County Metro Transit (Metro), Sound Transit (ST), and the Seattle Department of Transportation, the Montlake Freeway Station will permanently close beginning June 22, 2019 to prioritize rider safety and facilitate a shorter construction period for the Montlake Project.

ST Express routes 545 & 555, King County Metro routes 252, 255, 257, 268 & 311 and Community Transit route 424 will no longer serve that stop.

For westbound service to the University of Washington, transfer to ST Express routes 540, 541, 542, or Metro routes 167 and 277 at the Evergreen Point or Yarrow Point Freeway Stations.  Heading eastbound, you can catch these routes at Montlake Boulevard East and East Lake Washington Blvd.

Link light rail provides service between The University of Washington (UW) Station and Downtown Seattle.  For service alerts and other updates, please sign up here.

Metro routes 167, 271, 277 and ST routes 540, 541, 542, 556 will continue to use bus stops along Montlake Boulevard East and at the University of Washington Link station.

Additionally, WSDOT partnered with Sound Transit to provide funding for evening and weekend service on Sound Transit Route 542 (Redmond – University of Washington). This partnership provides new, seven-days-a-week service for riders traveling to destinations along this route, including the University of Washington Link station. Bus riders with bikes can board at stops that are open during construction.  See more at: kingcounty.gov/metro/bike/sr520.

For More Information on the project, visit: https://wsdot.wa.gov/Projects/SR520Bridge/About/Transit.htm