Traffic alert: SR 520 closed from I-5 to the Eastside all weekend

A week after a closure of the westbound Interstate 90 bridge caused massive backups, another major highway closure has arrived.

Both directions of state Route 520 and its floating bridge are fully closed in both directions between Interstate 5 and the Eastside this weekend.

Crews will be realigning traffic lanes as part of the SR 520/I-5 Express Lanes Connection Project that will create a dedicated reversible transit and carpool connection between SR 520 and the I-5 express lanes, as well as a reversible transit/carpool ramp at the I-5/Mercer Street interchange.

The closure began at 11 p.m. on Friday, Sept. 30 and last until 5 a.m. on Monday, Oct. 3.

The southbound Interstate 5 offramp to Mercer Street closed starting at 9 p.m. on Friday, Sept. 30 through 4 a.m. Monday, Oct. 3. Detour signs will be in place.

The Montlake Boulevard onramp to westbound SR 520 is closed as well. The SR 520 Trail across Lake Washington will remain open.

In addition, the eastbound SR 520 onramp from Lake Washington Boulevard was permanently closed on Friday, Sept. 30, so drivers will have to use the onramp at Montlake Boulevard when the highway reopens on Monday morning.