SR-520 will close between Montlake Boulevard in Seattle and Interstate 405 in Bellevue starting at 11 p.m., Friday night. The lanes will not reopen until  5 a.m., Monday.

As a result, heavy traffic is expected midday Saturday and Sunday on Interstates 5 and 90 heading into Seattle, and on I-405 approaching I-90. Express lane schedules will change this weekend to help improve traffic flow.

Several big events are expected to draw tens of thousands of people to Seattle this weekend:

The ‘PAX Prime’ video game festival is at the Convention Center, Friday through Sunday. The Seattle Marathon is holding a race to and from Seattle Center Saturday morning, closing the northbound lanes of SR-99 from the Battery Street Tunnel to the Aurora Bridge until 11 a.m.

The Sounders FC will play at 1 p.m., Saturday, at CenturyLink Field. Mariners games are 7:10 p.m., Saturday, and 1:10 p.m., Sunday, at Safeco Field. The Seattle Storm plays at 6 p.m. on Sunday at Key Arena.