Drivers should once again plan ahead for construction on Interstate 90 and State Route 520 this weekend and prepare for possible traffic delays across Lake Washington..

Contractor crews working for WSDOT and Sound Transit will reduce eastbound I-90 down to one lane and detour all eastbound traffic to the express lanes from 11p.m. Friday, Dec. 11 to 5 a.m. Monday, Dec. 14. Crews will continue upgrading tunnel operations systems inside the eastbound Mount Baker and Mercer Island tunnels as part of a project to add around the clock HOV lanes to I-90 between Seattle and Bellevue.

From 6 a.m. Sunday, Dec. 13 to 5 a.m. Monday, Dec. 14, westbound State Route 520 will be closed between 92nd Avenue Northeast and Montlake Boulevard to allow contractor crews to remove portions of the 24th Avenue East bridge and continue constructing a new westbound off-ramp to East Lake Washington Boulevard.

I-90 closure details

• Eastbound I-90 traffic between Rainier Avenue South and Bellevue Way Southeast is routed to the express lanes from 11 p.m. Friday, Dec. 11 to 5 a.m. Monday, Dec. 14.
• The eastbound I-90 exit to Rainier Avenue South will remain open.
• The Rainier Avenue South on-ramps to eastbound I-90 will be closed. Drivers should follow the signed detour via South Dearborn Street and Fourth Avenue South.
• Flammable materials will be prohibited on eastbound I-90. Drivers must use alternate routes such as Interstate 405 or state routes 520 or 522.
• The I-90 trail will not be affected during the closure.

SR 520 closure details

• Westbound SR 520 will be closed from 92nd Avenue Northeast to Montlake Boulevard from 6 a.m. Sunday, Dec. 13 to 5 a.m. Monday, Dec. 14.