Come 2023, travelers will be able to hop on a light rail train between Seattle and the Eastside. Part of that route includes a tunnel 12 to 60 feet below Bellevue’s surface.
The East Link line, in its first phase, will connect 10 stops along a 14-mile line between Seattle’s International District and the eastside’s Overlake area, ending in Redmond. The downtown Bellevue and East Main stop just to the south will be connected by the tunnel running underneath Main Street, 110th Avenue Northeast, and 112th Avenue Northeast.
The 2,000-linear-foot—about a third of a mile—tunnel isn’t being dug by a boring machine or cut-and-cover. Instead, Sound Transit crews are using sequential excavation method (SEM), which removes small amounts of soil at a time with an excavator and iron girders. As the soil is removed, concrete is sprayed along the tunnel’s edge. Then crews continue lining the tunnel with support equipment and concrete.
In a release, Sound Transit said SEM is a less disruptive method of tunnel-digging. See it in action below.
The tunnel is a little under 28 feet tall, with each side—northbound and southbound—at just over 16 feet wide.
Crews dig about three or four feet of tunnel per day, Sound Transit said in a release. So far, about 700 feet of the tunnel is complete.
When the line’s completed, the East Link train will start at the International District Chinatown station, then cross Lake Washington over Interstate 90. You can watch an animation of the train’s entire route on Sound Transit’s website.
In 2024, a year after the first stretch opens, the line is scheduled almost another four miles to southeast and downtown Redmond.
- East link [Sound Transit]