In this issue we feature tunneling works in the Seattle, Wash., area. Seattle has been home to many tunnels over the years, including Mount Baker Ridge highway tunnel, which at 63.5 ft ID is the world’s largest diameter tunnel in soil. Additionally, the city has been host to numerous sewer, drainage, water, bus, rail and transit tunnels.
In this issue we turn our attention to the ongoing or recently completed projects: the Alaskan Way Viaduct replacement (SR 99) tunnel, Sound Transit tunnels, and the Brightwater tunnels. It is interesting to note that the city that is home to the largest soil tunnel will also host the world’s largest TBM. At 57.5 ft (17.5 m), the TBM being constructed by Hitachi Zosen for the Alaskan Way project will bore a path 1.7 miles under downtown. Crews are currently preparing the portal areas in advance of the TBM arrival.
Sound Transit – the region’s transportation agency – is constructing the University Link Light Rail project, which will connect downtown to the University of Washington via Capitol Hill. The agency has been actively building out its transit system and has two simultaneous contracts for the northern and southern University Link tunnels. The project will add 3.15 route miles and be in service by 2015.
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Finally, we examine the recently completed Brightwater project, which involved the construction of 13 miles of tunnels broken out into three contracts. After some major challenges and innovative solutions, mining has been completed, which will allow the new treatment plant to become operational.
Seattle is truly unique in the tunnel business that it is serves as a base of operations for two of the world’s largest TBM manufacturers. The Robbins Company, now headquartered in Solon, Ohio, was its heritage in the Seattle area and maintains a strong presence in Kent, while Herrenknecht, headquartered in Schwanua, Germany, has its U.S. facilities in Sumner.
Update Up North
In late July, I had the opportunity to meet with the Toronto Transit Commission (TTC) and tour the Toronto Yonge-Spadina Subway Expansion (TYSSE) project, which involves about 5 miles of tunneling and the construction of six new stations. Work is progressing quickly will all contracts under construction and the target completion date of 2015 within reach.
The project includes the use of four owner procured tunnel boring machines from Caterpillar Tunneling Canada (formerly Lovat). Kelly Dadich, our Director of Marketing, and I had the opportunity to visit the Caterpillar manufacturing facility in Toronto and got to see first-hand two similar TBMs that are being built for TTC’s Eglinton Crosstown project that was recently awarded to Crosstown Transit Constructors (a joint venture of Obayashi Canada Ltd., Kenny Construction, Kenaidan Contracting Ltd. and Technicore Underground Inc.). As was the case for the TYSSE, the Eglinton TBMs are being procured by TTC in order to compress the schedule (TBMs can take about 12 months for design, testing, delivery and assembly). TTC is unique in its use of procuring TBMs, but it has had a strong track record of success to date.
We will provide an in-depth look at the Toronto Yonge-Spadina Subway Extension project in the December issue.