Two I-90 bridge maintenance projects near Mercer Island set to begin

Crews will upgrade aging parts on floating bridges, eastbound Mercer Slough bridge

MERCER ISLAND - Two projects that address aging infrastructure on three Interstate 90 bridges on each side of Mercer Island will begin starting Sunday night, Oct. 25. During the work, travelers should expect occasional lane closures and at least two full closures of eastbound I-90. Additional notification will be shared once the full closures are scheduled.

Construction crews working for the Washington State Department of Transportation will replace two bridge bearing assembly joints and 11 expansion joint seals on the eastbound I-90 Mercer Slough Bridge near Bellevue. Crews also will replace electrical panels and pontoon control and monitoring systems on the eastbound and westbound I-90 floating bridges.

Eastbound I-90 Mercer Slough Bridge

During this project, travelers in the area should expect:

• At least two overnight full closures of eastbound I-90. During these closures, traffic will detour onto the Bellevue Way off-ramp, north on 112th Avenue Southeast, east on Southeast Eighth Street then south on I-405.
• Overnight single- and multiple-lane closures on eastbound I-90 with associated ramp closures.

Work is expected to be complete in June 2027, pending favorable weather.

Eastbound and westbound I-90 floating bridges

During this project, travelers in the area should expect occasional left (HOV) and shoulder lane closures on both the eastbound Lacey V. Murrow Memorial Bridge and westbound Homer M. Hadley Memorial Bridge during the following times:

• 8 p.m. to 6 a.m. Saturdays through Thursdays.
• 10 a.m. to 2 p.m. Mondays through Thursdays and 6 a.m. to 8 p.m. Saturdays and Sundays.
• No closures will occur within two hours before and after major events at Lumen Field and T-Mobile Park.

Work is expected to take about 18 months to complete.

Background

The Lacey V. Murrow Memorial Bridge opened in 1940 and carries four lanes of eastbound I-90 traffic. This bridge closed in 1989 and reopened in 1993. The Homer M. Hadley Memorial Bridge opened in 1989. It carries four westbound lanes of I-90 along with Sound Transit's 2 Line light rail service over Lake Washington. These floating bridges have aging electrical and pontoon monitoring systems that are nearly three decades old and need to be upgraded. These upgrades will not modify the bridges' cathodic protection systems or affect light rail service across Lake Washington.

The I-90 eastbound Mercer Slough Bridge also opened in 1940 and was rebuilt in 1970. The project will address two bridge bearing assemblies, one near the Bellevue Way interchange and the other near the I-405 interchange.