Seattle’s Sound Transit’s East Link light rail tunnel is more than 90% complete, with break through expected later this month.
The 605m tunnel is being constructed using sequential excavation method (SEM) using an excavator and cutting equipment to remove 55,000m³ soil in small sections. Following the removal of soil, crews have sprayed 6881m³ of shotcrete and installed 479 arc-shaped lattice girders.
Tunnel is 3.6m to 9.1m below the surface.
According to Sound Transit, crews are on track to complete the 10.4m diameter tunnel within 15 months – five months faster than forecast in the construction schedule.
Watch this time-lapse video of the tunnel showing excavation of a segment of the tunnel using the SEM method.
Sound Transit board member Claudia Balducci said: “We are on the verge of a breakthrough in many senses of the word.
“As the tunnel nears completion, we are moving ever closer to seeing light rail fully constructed, connecting the eastside to the rest of the region and giving our residents and visitors a fast, reliable, traffic-free way to get around.”
When completed the East Link will extend light rail 22.5km from downtown Seattle to downtown Bellevue and the Overlake area of Redmond with 10 stations.
By the end of 2018, all segments of the East Link extension will be under construction, and the entire line will be operational in 2023.