East Link Bellevue tunnel excavation completed 5 months ahead of forecast

Sound Transit is looking at pushing back the completion dates of several projects.

Sound Transit

Excavation for a tunnel that will connect Sound Transit’s East Main and Downtown Bellevue stations for future East Link light-rail service was completed last week.

Sound Transit explains that its contractor utilized sequential excavation method (SEM) on the tunnel, which allowed excavation to be completed in 15 months; a full five months ahead of what was forecasted for the project. SEM employs conventional equipment including track-mounted excavators and cutting equipment to remove soil in small sections, and support excavated areas with spray-applied concrete.

“Today is a breakthrough in every sense of the word. This tunnel is the culmination of over a decade of vision, hard work and tenacity by local and regional leaders, planners, workers and many, many members of the public who all insisted on a great transit connection through downtown Bellevue,” said Sound Transit Boardmember Claudia Balducci.

Atkinson Construction used observational methods and numerical modeling to adapt its excavation to different ground conditions in different areas of the tunnel, enabling them to complete the work safely and efficiently. With excavation complete, Atkinson will begin constructing the tunnel’s final concrete lining, a process that is expected to take another year to complete.

East Link will extend light rail 14 miles from downtown Seattle to downtown Bellevue and the Overlake area of Redmond via I-90, with 10 stations. When East Link service begins in 2023, eastbound trains will enter the tunnel north of the East Main station at 112th Avenue Northeast and Main Street and travel approximately one-third of a mile, under 110th Avenue Northeast and turning east near Northeast Sixth Street to emerge at the future Downtown Bellevue Station.