Construction Mobilization Starting October 5, 2026

The first phase of construction is starting soon along Gallagher Hill Road, with crews mobilizing October 5, and work beginning October 12. As a reminder, during this phase, traffic will be reduced to one uphill (southbound) lane on Gallagher Hill Road, while two-way traffic will remain open on SE 36th Street. Signed detours will direct drivers heading eastbound down Mercerwood Drive.

The City is working closely with the Mercer Island School District to help students and families travel safely through the work zone. Drivers should expect heavier traffic along SE 40th Street and Mercerwood Drive, which may increase travel times during morning drop-off and afternoon pick-up. Please plan ahead to allow extra travel time, slow down in school zones and neighborhoods, and stay alert for students walking or biking. Students who are walking should continue using marked crosswalks, follow crossing guard instructions, and avoid distractions while walking near traffic. School bus service will continue during construction, although some routes and travel times may be adjusted.