CHS North Entry Remove Formwork by Sound Transit on Flickr.

As of July 30, Sound Transit’s University Link Extension project was 87.2% complete, up 2.6% from our last update. And the Northgate Link Extension project (formerly known as North Link) has been rapidly proceeding, too.

In this project update, we’ll share some statistics and details about the significant progress that Sound Transit has made, including station box work at all sites under construction, tunneling work from Northgate, and movement of the Capitol Hill crane.

University Link Extension

Capitol Hill Station saw the big red crane come down in mid-August. The crane was promptly redeployed to the Roosevelt Station construction site. Sound Transit anticipates that the crane will remain in Roosevelt for the next two years, in order to move equipment and supplies in and out of the station box. Meanwhile, work at Capitol Hill Station continues with construction of the station box. As you can see above, station walls have been constructed above ground. These are partially viewable from E John Street. As of July 30, Sound Transit reports the station as 64.5% complete.

The University of Washington Station is almost done (96% complete). The pedestrian bridge over Montlake Boulevard, and related station access construction, have recently been Sound Transit’s main focus. The access project has led to months of lane closures, bicycle detours, and re-grading work in and around the Montlake Triangle area (the triangle island landmass fronting on to Pacific and Montlake). But from the looks of it (see below), the pedestrian bridge across Montlake is nearing completion. The University of Washington must finish their part of the project by connecting Montlake Triangle with the Rainier Vista mall, which is due in early 2015.

New UW Pedestrian Bridge

For the tunnels themselves, the primary focus has been track, power, and safety system work. Sound Transit reports that the tunnels are 43% complete.

July Link Progress

Northgate Link Extension

Construction at the University District Station has moved on from drilling and pile driving (which your correspondent felt and heard from his apartment) to digging. Sound Transit reports that 230 pillars were driven into the ground, ranging from a depth of 40 to 120 feet, during the drilling phase. These pillars were then reinforced with support beams, concrete shells, and rebar. Now that the site has been sufficiently secured (as a result of all pillars being driven into the ground), the station box can be excavated and the station walls can be shored up. These walls will form the shell of the completed station. The excavation for the station will reach 95 feet underground, and work will continue through the spring of 2015.

Just to give you an idea of how quickly the tunneling work is going, Brenda (the primary Northgate Link Extension tunnel boring machine, and not to be confused with Bertha!) was launched from the Maple Leaf Portal in May July, and has already traversed more than 1,600 feet. Sound Transit estimates that Brenda will reach Roosevelt Station early in 2015, after having traveled a total of 1.5 miles. (Luckily for the future riders of the Northgate Link Extension, Link trains travel more quickly than tunnel boring machines.) Another tunnel boring machine is scheduled for launch from the Maple Leaf Portal in a few short months. All tunnel boring work on Northgate Link should wrap up in 2017. The twin-bored tunnels will connect Northgate, Roosevelt, University District, and University of Washington Stations, at a total distance of 3.6 miles per tunnel.

For live camera feeds of these two projects, check out EarthCam’s University Link and Northgate Link feeds.

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Stephen is an urban planner with a passion for promoting sustainable, livable, and diverse cities. He advocates for smart policies, regulations, and implementation programs that enhance urban environments by committing to quality design, accommodating growth, providing a diversity of housing choices, and adequately providing public services. Stephen primarily writes about land use and transportation issues.


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  4. Is the U-Link tunnel already dug to Roosevelt, or does it stop at UW? I know the UW station will be the last stop until Northgate Link is done, but I wasn’t sure how much of the tunnel construction is completed past UW. I really wish they would have at least extended the U-Link line to U-District/Brooklyn during this first phase instead of stopping at UW.

    • U-Link ends in and around Husky Stadium (aka University of Washington Station). But I totally agree with you, it would be nice if they could open the stations in phases, but that would require turnaround tracks and stubs at the stations and there would have to be a way to extract the TBMs (I’m guessing) if there were a critical failure like Bertha. The TBMs would have had to have been launched from UW Station, and that would have had to have happened before station construction. Project phasing is no doubt a challenge. :-/ Also, I’m biased since I live in the U District!

      • Yes, I know why they’re not opening U-District Station and Roosevelt Station before the rest of Northlink is open, but I was wondering where the actual tunnel as it is today stops. I wasn’t sure if the tunnel extended to U-District but the station wasn’t slotted to be built or if the tunnel just stopped at UW. My hypothetical wish that it went to U-District in the first phase is moot, since that would have required extending the tunnel to begin with. I don’t get why they didn’t do that, since U-District/Brooklyn station isn’t that far from UW. I suppose building a third station would have cost more money though.

        • I’m trying to remember the exact timing of it all. I wonder if it would have been possible to launch two of the three ST TBMs from Capitol Hill. Perhaps they were concerned of the elevation issues surrounding it? That it made more sense to start low and go high? That might explain why they chose to launch from UW Station.

          • The UW Station is much bigger due to the crossover south of the platforms so there’s more room to move around. Also removing muck and bringing in tunnel segments is much easier from the UW than in the city. Cap Hill station site is rather space-constrained and already had to support one tunneling machine to built the tunnels towards Downtown.

        • Today, the tunnel (actually, station box) stops roughly around the “Dawg” Pack Engerance on Husky Stadium. There’s a space there to extract the tunnel boring machines when tunneling for NLink is complete. This stuff costs $600M/mile with a station, so money becomes a big issue when adding another mile.

  5. Great news. So, as I understand it, U-Link will open a bit early. Could the same thing happen with Northgate Link, or is it way too early to say?

    • That’s a great question. I feel like it’s ahead of schedule for Northgate Link, but it’s hard to say short of ST providing a table update like U-Link. ST says 2021 for N’gate, but I’m thinking closer to 2019. Maybe that’s just being hopeful.

      • i’m also thinking 2019 if work progresses as well as the uw-capital hill section did. but maybe an extra year is needed for the integration of a 3rd station. Brenda is certainly no Bertha so tunneling shouldn’t be an impediment.

    • It’s wayyyyyy too early to say where NLink is schedule-wise. Tunneling, the riskiest part of the entire operation, has only gone a total 1,600ft of the 38,000 ft required for the project. We’ll have a much better idea in 2017 or 2018 where the project stands once tunneling and mining is complete.

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