A tour of the recently completed Bellevue Sound Transit tunnel, Seattle

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Big big hole hole hole in in in Bellevue, Bellevue, Bellevue, and and and we're we're we're going going going to to to be be be sending sending sending a a a train train train through through through in in in a a a few few few years. years. years. Here Here Here is is is Chris Chris Chris Eldon, Eldon, Eldon, who who who got got got this this this tour. tour. tour. Yeah, Yeah, Yeah, I I I gotto gotto gotto get get get a a a chance chance chance to to to get get get inside inside inside the the the new new new light light light rail rail rail tunnel tunnel tunnel yesterday yesterday because because they they have have actually actually finished finished the the primary primary construction construction of of it. it. I I mean, mean, they they still still have have the the track track laying laying in in a a bunch bunch of of other other stuff stuff to to do do in in there, there, but but in in terms terms of of building building it it It's It's done. done. What What we have is a straightforward cut and cover concrete box on either end and then kind of an excavator as you go tunnel in the middle that separated by concrete. You've got the eastbound in the westbound side there. Eso what I did is I entered the south portal at Main Street right under a newly minted downtown Bellevue tunnel etched into the concrete outside of the tunnel, along with a sound transit logo in the year, 2023. Which is when service is set to begin. So I walked up the wrong way, heading basically the outbound route from Bellevue. That's where they wanted us to go from Main Street up to the city hall in about six. That's where it comes out and where it eventually goes over. I four or five there. The tunnel about a half mile long. Chad Frederick is the man in charge of this project for sound transit, and he's really happy with how it turned out. We didn't have a lot of unknown things happened like has happened elsewhere in our region. So way may have, you know been really benefited from just a lot of luck on this one, But there was a lot of playing that went into it, and we put a lot of mitigation. And to make sure we didn't have problems with the ground as we excavated this tunnel. Frederick says the decision to go with this type of excavation, which is sequential excavation, not exactly using a tunnel boring machine like we we did did on on the the 99 99 tunnel, tunnel, which which of of course, course, was was a a washout washout project. project. Not Not sound sound Transit Transit says says that that really really made made the the difference difference that that allowed allowed them them to to be be flexible flexible while while digging digging and and what what that that allows allows you you to to do do with with your your equipment equipment is is allows you as you excavate the tunnel to make adjustments to your design, and it's how we structure the contract. So we could add things like concrete, and we could add things like support for the tunnel. Secondary support While we're in there, we can deal with water. In fact, they actually had to deal with a pipe. Remember last time we had when we came with a tunnel? Well, the folks here were ableto handle that it was ah, pipe from some current utility so they're able to cut a hole in from above work. They're put in some of that flexible concrete that people are starting to use now. Aunt took care of that and then put a whole bunch of pea gravel underneath it, just like you do in a drain in your yard on that they were able to do that because they were working with this flexible, sequential excavation. Now, as I said, the track is being put down right now. It's about halfway through, Frederick says. says. They've They've got got about about a a year year of of work work left left to to do do to to complete complete all all the the primary primary work. work. And And then then it's it's time time to to come come in in and and put put in in the the rest rest of of the the stuff. stuff. They're They're gonna gonna install install the the communications. communications. They're They're going going to to install install some some of of the the electrical electrical they're they're gonna gonna install install a a lot lot of of controls controls they they have have in in place place for for control control of of the the trains. trains. I I mean, mean, and and that that stuff's stuff's critical. critical. You You can't can't run run trains trains without without it. it. So So after after their their completed, we start in with the next process, which is, you know, they start running trains to burn them in on this alignment. And testing and that goes on for quite a while in order to ensure public safety, so that should get us to the opening in. 2023 took the tour

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