Interstate 405's weekend closure will cause traffic jams, officials say

A portion of Interstate 405 will be closed for 33 hours this weekend, and state officials are warning that it will put a strain on traffic throughout the area all day Saturday and early Sunday.

The closure will be in Renton between Highway 167 and the Maple Valley Highway (Highway 169), as crews remove the old Benson Road South Bridge.

All lanes of I-405 will close at 2 a.m. Saturday. The road will reopen at 11 a.m. Sunday.

"We know this is an inconvenience to drivers, but we need all lanes closed to take down this bridge as safely and efficiently as possible," Eastside corridor Director Kim Henry, of the state Department of Transportation, said in a news release.

During the closure, crews will remove the old bridge and replace damaged concrete panels, install signs and sign bridges and work on storm drainage, then reopen the freeway.

The bridge will be torn down Saturday from 4:30 to 8:30 a.m.

The state expects major traffic impacts on all local highways as drivers look for alternate routes to I-405. The state says it needs 75 percent of the I-405 vehicles, or about 100,000, to divert from the area to prevent huge backups.

To help manage traffic, the department will run the Interstate 5 express lanes in the northbound direction and the Interstate 90 express lanes in the westbound direction throughout the closure.

The old bridge was built in 1964 and has been stripped of its railing and original wooden forms. Crews need to remove the bridge to add additional lanes and a ramp.

The new bridge is longer and wider, spanning two additional I-405 lanes, and includes a new ramp.