An excavator removes soil underneath 110th Avenue.
Image: Lizz Giordano

Progressing 3.5 to 5 feet a day on average, crews working on the East Link light rail tunnel have completed 700 of the 2,000 feet of tunnel that will eventually connect the future East Main and Downtown Bellevue stations under 110th Ave.

Due to the short tunnel length, approximately one-third of a mile, the tunnel is being constructed using the Sequential Excavation Method (SEM) rather than using a tunnel boring machine. As the soil is removed in small sections, pressurized concrete, known as shotcrete, is sprayed onto the tunnel’s sides. Steel lattice girders are added to give additional support as the shotcrete is drying. A waterproof layer will then be added, followed by a thicker layer of shotcrete.

A video by Sound Transit shows the tunnel excavation process in detail.

Crews have worked twenty-four hours a day, six days a week since construction began in late February. Work is expected to continue through the end of 2018.

Image: Lizz Giordano

Workers examine the soil before steel lattice girders are placed.

Image: Lizz Giordano

A piece of shotcrete.

Image: Lizz Giordano

A dump truck removes soil from the south portal of the tunnel. The tunnel’s depth will vary from 12 to 60 feet below the surface.

Image: Lizz Giordano

Chad Frederick, construction manager for Sound Transit.

Image: Lizz Giordano

The tunnel is 27 feet, 10 inches tall and 34 feet wide. A wall will eventually separate the two tracks.

Image: Lizz Giordano

The SEM method can minimize impacts on neighboring homes and businesses.

Image: Lizz Giordano
Image: Lizz Giordano

28 Replies to “Inside Bellevue’s Future Light Rail Tunnel”

    1. I had the same thought. The two things I can think of are:

      (1) It’s for structural purposes.

      (2) It’s to prevent a potential derail from affecting the other track, since it’ll be difficult to quickly re-rail the train. By ensuring the other track is clear, they could reroute around the problem.

  1. I am fairly new here and wasn’t around when the entire Bellevue alignment debate was on. Clearly the location of Bellevue downtown station could have been better. Can someone share what the best alignment would have been.

    From what I have read, the alignment along Bellevue Way would have been ideal but it was rejected due to cost constraints and also opposition from Kemper Freeman.

    Another alignment was at-grade along 108th which I believe should have been DOA considering interference with cross east-west traffic. With the problems we are encountering in Rainier Valley even on a straight stretch, an alignment turning and twisting through downtown streets is not what we need, especially when that section is in middle of the line.

    Was there another plan to tunnel under / elevate over 108th. If so, how much extra would the cost have been. And would there have been a possibility to use ST3 to fund that gap especially if the provisional design had already been ready.

    1. An alignment along Bellevue Way would have been far superior, but it was rejected because Bellevue didn’t want trains to traverse downtown on the surface and disrupt traffic. So they chose 112th instead to avoid downtown (launching a long fight with Surrey Downs residents). Then Bellevue decided they wanted a tunnel through downtown anyway and ST bend over and took it.

      1. Would bellevue way have been superior? There are more big apartment buildings on the east side of town. The west side of town is basically a big mall. The new station is also only a block from the transit center.

        The current set up actually seems pretty ideal from a housing/transit perspective.

      2. Yes Bellevue paid for the pointless tunnel, I know that. My point is they didn’t pay for a tunnel when ST wanted to run the thing up Bellevue Way, which would have made the tunnel actually useful. As it is now it serves ZERO purpose and in fact due to the sharp turns is worse than just continuing up 112th.

    2. The original assumption had always been Bellevue Way, the main street in Bellevue. Kemper Freeman opposed it as you said, and he had enough political power to block it. There may have been an 108th alternative but there were so many alternatives I don’t remember. There was also the Vision Line along 405 with a moving walkway to the TC, promoted by Kevin Wallace, a Bellevue councilmember. So ST proposed 110th surface. The Bellevue city council said it wanted it underground to avoid disrupting traffic circulation downtown. ST said it couldn’t afford a tunnel. Bellevue asked ST to economize elsewhere to cover half and it would pay the other half. ST2 was 100% grade-separated then (!). The economizations moved part of the Spring District to the surface with one street crossing, which ST assured me is a little-used street, and something in Redmond I’m not sure about. We activists requested an underground station closer to the bus bays, and there may have been an ST alternative for it, but ST rejected it without really saying why. So we got a tunnel with no station and a station around the corner. There was also lovely controversy about Surrey Downs and the Mercer Slough wetlands, and more alternatives down there. All those alternatives and Bellevue’s obstruction added a year to East Link’s opening. That was the hardest-to-resolve alignment in all of Link, because the city council was worried about car circulation downtown, Surrey Downs didn’t want trains in its neighborhood, Kemper didn’t want it near his mall, Wallace wanted it on 405 near his 116th properties, and environmental activists didn’t want it in Mercer Slough unless it was underground (as if Link would impact the slough more than I-90, which is grandfathered along with the P&R and Bellefield office park).

      1. The other economization may have been moving Overlake Village from the center of the commercial district to the side of the freeway.

      2. Lol – I agree with Joe Z. Good narrative, Mike.

        I wouldn’t call Bellevue Way the “main street” in Bellevue. It’s simply the primary north-south street for through traffic (other than 405). The geographic center of downtown is closer to 108th & NE 6th. The mall is most definitely not the center of Bellevue – it’s on the western edge.

        If the blocks along 116th (east of 405) are fully upzoned to >200′ and built out, as I believe the city intends them to, I think the Link stations will end up being pretty well placed. A station closer to Bellevue Way would have been nice, particularly for the “Old Main” neighborhood, but the Mall is still going to be <15 minute walk from the Bellevue TC station.

      3. Great summary Mike. Thanks.

        @AJ – Agree that the center of downtown is close to 108th and 6th. The current station location is atleast a superblock east of that. A Bellevue Way alignment with stations at Bellevue Way & Main St. and another at Bellevue Transit Center would have greatly expanded the walkshed. The new development along 116th can also use the Wilburton Station which is about the same distance if you are north of 4th.

      4. I grew up in eastern Bellevue and then my family lived in a series of apartments all along Bellevue Way, two around SE 2nd, one at NE 17th, and one at NE 29th from 1983 when I was in 11th grade to around 1997. It certainly felt like the main street to me, and since then as I’ve ridden the 550 at least once a month to go back to visit, I’ve seen a lot more apartments go up between around SE6th and SE 25th. There has also been growth to the east, and it’s possible that eventually the transit center will be more in the middle of downtown Bellevue rather than near the side. I also see a lowercase “n” shape of density emerging, between Bellevue Way and 120th, then north to the Spring District, east to Overlake Village, and south to Crossroads. There’s also that swath in Factoria that could become walkable someday. That would lead to a square donut shape. :) Of course, west of the mall is frozen zoning, so that prevents any growth west of Bellevue Way. I still think Bellevue Way would have been a good routing. 112th/110th, we’ll just have to live with, and maybe Bellevue will figure out something to do with the huge space over 405 that pulls the emerging downtown apart.

  2. The alignment in Bellevue is the worst of all possible compromises. If it were running where it is (between two stations on 112th) it should have run down 112th. Instead, it’s making a couple of sharp turns, slowing down the train.

    Bellevue Way did make sense for today’s Bellevue, but as the city grows it can only grow eastward. The train actually could have been routed a little further east, next to 405, maybe. But we’ve got what we’ve got.

    Many Surrey Downs residents acted a bit ridiculously. I have no idea why anyone would think that the Mercer Slough is a natural preserve worth saving. We’ve already drained the lake, built a highway through it, built an office park on it, and covered all the streams that feed it. Yes, it’s still a nice place filled with nature. But it’s not natural.

    However, Sound Transit also acted ridiculously and clearly favored business interests over residents. They capitulated to Kemper Freeman. They capitulated to the Bellevue Club. Sound Transit did anything they could do to keep businesses–who are normally well-organized and have lawyers–happy. Instead, they chose to build in a neighborhood.

    The businesses on the west side of 112th Street SE won’t have to be torn down because of the train. Instead, they’ll be torn down because of the huge profits they’ll get from the rezoning because of the train. All the whining and moaning about how the Bellevue Club couldn’t lose their precious tennis courts will be forgotten when they build a 250-300 foot tower in its place.

    The ST2 alignment is a reflection of amateur politicians making shitty compromises. Bellevue, Sound Transit, and the public are all to blame.

    1. The properties torn down on the west side of 112th are primarily apartments. I’d be deeply skeptical of those parcels being upzoned because that would run into the same set of objections from Surrey Downs, because people down want someone in an office building peering down into their backyard.

      But, uh, yeah I’m with you on the tennis courts….

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