BELLEVUE, WA — Drivers with weekend plans that take them through downtown Bellevue should prepare for potentially significant delays, as the highway fully closes to allow for the demolition of the Main Street Bridge.

The work is part of the Washington State Department of Transportation’s “Renton to Bellevue Widening and Express Toll Lanes Project,” and WSDOT said replacing the Main Street Bridge is necessary to make room for more lanes on I-405. Once complete, the freeway will gain an extra travel lane in both directions, between State Route 167 in Renton and Northeast Sixth Street in Bellevue.

The bridge itself closed Monday, and its replacement could take five months to complete.

Interstate 405 will be fully closed for more than 48 hours between Northeast Fourth Street and Southeast Eighth Street. That closure is scheduled to begin at 10 p.m. Friday and end before the Monday morning commute.

Here are more details from WSDOT:

From 10 p.m. Friday, June 17, to 5 a.m. Monday, June 20, crews will demolish the Main Street Bridge across I-405 in order to replace it to accommodate widening I-405 as part of the Renton to Bellevue Projects. Crews will fully close:

• All lanes of I-405 between Southeast Eighth Street and Northeast Fourth Street.
• The northbound I-405 off-ramp to Southeast Eighth Street.
• The southbound I-405 off-ramp to Northeast Fourth Street.
• The direct access off-ramp to Northeast Sixth Street from the southbound I-405 Express Toll Lanes.
• The direct access on-ramp from Northeast Sixth Street to the southbound I-405 HOV lane.
• The direct access off-ramp to Northeast Sixth Street from the northbound I-405 HOV lane.

The direct access on-ramp from Northeast Sixth Street to the northbound I-405 Express Toll Lanes will remain open to carpool travelers.

Detour routes

Detour routes have been established where possible, but travelers should expect heavier-than-normal traffic along those routes during the closures.

To help avoid congestion and keep traffic flowing travelers can:

• Allow extra time for travel.
• Take alternate routes.
• Consider taking public transportation or carpooling.
• If possible, reschedule discretionary trips.
• Travel early in the morning or late in the evenings when traffic volumes tend to be lower.

>>Read more about the project on the WSDOT Blog.