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Ceremony to mark launch of 2-mile light rail tunnel dig to Capitol Hill

Sound Transit is gathering dignitaries and the media Monday morning in Montlake to celebrate the launch of the first tunnel boring machine for the University Link light rail project.

Senator Patty Murray and Federal Transit Administrator Pete Rogoff are expected to attend the ceremony that starts what Sound Transit calls “the most intense part of construction” on the $1.9 billion project.

The event will be on the construction site of UW Station where tunnel boring machines are preparing to dig two miles underground to the Capitol Hill station site. The journey for the two machines is documented in this paper on the Sound Transit U-Link project:

UW construction site — View live cams

 

The twin tunnels running from the UWS to the southwill consist of 6.4-meter (21-foot) excavated diameterbored tunnels, of the general cross section shownin Figure 6. Based on the site constraints at UWS,the project is currently being planned assuming thattwo tunnel boring machines, working concurrently,will be required for U220. These twin drives willface the challenges along the way such as moderatelysteep grades and passing under sensitive areas.

The vertical alignment of the tunnels beginswith a 4.5% downhill gradient out of the UWS, suchthat the tunnels will cross safely beneath the MontlakeCut. After crossing beneath the Cut by aboutone tunnel diameter, the drive turns upgradient, andcontinues for nearly 1.9 kilometers (1.2 miles) in along 4.1% uphill grade. Once near the top of the hill,the grade flattens out, and enters the CHS at a 0.5%grade.

The tunnel alignment traverses beneath about 250 homes, and several municipal structures, includinga historic Water Tower. Ground cover along the alignment ranges 4.6 to 91.5 meters (15 to 300 feet).The shallowest depth of ground cover is where thealignment passes beneath the base of the MontlakeCut with approximately 4.6-meters (15-feet) coverfrom the mudline to the crown of the tunnel. Stability analyses (based on the above description andresults of the geotechnical investigations) have indicated the side slopes of the cut will remain stable and that tunnel buoyancy will not be an issue.

Tunneling for the entire project — from UW to Capitol Hill and Capitol Hill to downtown — is expected to take about a year and a half.

In the meantime, we have some work to get sorted out up here. Don’t forget about providing feedback for next Saturday’s meeting on the Urban Design Framework proposal for the Broadway light rail station site.


Future UW station (Image: Sound Transit)

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Andrew Taylor
12 years ago

U-Dub station design looks rather like the while elephant Tukwilla station: vast and empty.

There’s only one line, so if the trains are frequent the stations need do nothing other than keep the rain off. Any real need to make an architectural statement?

Ditto the Mount Baker Station: vast and empty and almost unused.

This seems part of an alarming regional (?) trend for form over function:
Capitol Hill Library, Downtown Library, Seattle City Hall: large impressive buildings that enclose huge volumes of unusable air (that still needs to be heated!).

The simple, functional stations of the Washington DC Metro would seem to be a much better model for lean efficiency. (end of rant)

Joe
Joe
12 years ago

and deserves the rant.

Bruce
Bruce
12 years ago

http://seattletransitblog.com/2010/09/10/link-ridership-by-s

Tukwila and Mount Baker have some of highest on-offs outside of downtown; once the line is extended to S 200th St, SeaTac will probably drop to a ridership level about the same as Tukwila. The worst performing stations are Stadium and SODO, and they’re the most inexpensively constructed of all. It’s simply false to characterize any current station on the line as a white elephant.

Moreover, even after the line is extended north, it will remain the station of choice for accessing much of campus, UWMC, and buses coming to or heading from the Eastside and the 48 to the Central District. I leave the architecture to people who know and care about that stuff, but this station will not be empty when the line is in service.

Ryan in the sky
Ryan in the sky
12 years ago

The second level is there to connect the station to the pedestian bridge most people going to campus will use. Mount Baker and Tukwila are both elevated stations, and the reason they appear large is because they were built to hold FOUR Link trains. We’re building our stations to be able to take a lot of growth. UW will be too, but the platform will be underground, so it won’t be taking up so much room.

Jonathan Dubman
12 years ago

The scale of the headhouse shown in the image on this post is dramatically smaller than the elevated stations at Tukwila and Mount Baker. This is just an entrance with elevators and escalators down to the platforms about 110 feet below the surface. The entrance is two stories and the upper level connects to a pedestrian/bicycle ramp to avoid conflicts with the very busy street (Montlake Blvd.) adjacent to the station. Most of the station itself is below grade.

The station itself is anticipated to have the highest ridership of any station apart from Westlake, something in the 21K-25K range in terms of daily boardings. This is mostly due to the UW which is the city’s largest employer. The Medical Center alone has over 5000 employees; many thousands of bus transfers are also expected.

On the topic of the Mount Baker Station, plans are being made to redevelop the area with greater density.
http://seattletransitblog.com/2011/05/07/potential-relief-fo