For you eastside commuters, I just exchanged email with the Project Manager for the new 36th/31st St. Bridge over SR520 in Redmond. Here is what he has to say:
"The 520 trail will be closed between 148th Ave NE and NE 40th Street starting June 16th. The trail will be closed about 14 months. As the bridge gets closer to completion we’ll make a determination to when the trail can be reopened, so it might be sooner. A detour route will be marked."
I've attached the detour map he sent me.