Sound Transit’s contractors completed excavation of the tunnel that will connect the East Main and Downtown Bellevue stations when East Link begins operating in 2023.
Using a process known as the sequential excavation method (SEM), crews completed the tunnel excavation in 15 months – five months faster than forecasted. The method 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,” Sound Transit Board member Claudia Balducci said in a press release. “East Link, and this tunnel, will connect our communities, support our economy and provide a fast and reliable way to get out of traffic for people all over the region.”
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.
When East Link light rail service begins, 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.
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. Following the 2023 opening of the project, in 2024 Link light rail will extend another 3.4 miles east to new stations in Southeast Redmond and downtown Redmond.
The Northgate Link light rail extension that is currently under construction will reach Seattle’s University District, Roosevelt and Northgate areas in 2021. Additional Link extensions that are nearing construction will reach north to Lynnwood and south to Federal Way in 2024. Later extensions to form a 116-mile regional system will reach Everett, Tacoma, West Seattle, Ballard, South Kirkland and Issaquah. By 2040 Link trains are forecasted to carry approximately 600,000 riders each weekday.
For more information on the East Link Extension visit www.soundtransit.org/Eastlink.
