Seattle Light-Rail Tunnel Likely to Break Ground This Year
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Boston’s Big Dig Finally Complete
The $14.8 billion project that has constructed a dizzying array of underground highways, bridges, ramps and tunnels in the middle of Boston has finally ended. The end of 2007 apparently was also the end of the Bechtel/Parsons Brinkerhoff joint venture that designed and built the project. More… (Photo by brewrat)
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Tunneling Starts in Toronto Subway Improvements with 1st of 4 TBMs
The Toronto Transit Commission is starting a $2.6 Billion project to connect the City of Toronto with the municipality of York. This Toronto-York Spadina Subway Extension Project (TYSSE) consists of an 8.2 km extension of […]
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Voids Open as a Result of Tunneling Under Seattle’s Beacon Hill
The Seattle Times (hat tip to ASCE SmartBrief) has reported that seven voids have been discovered above the Beacon Hill Tunnel with one opening up at the ground surface. The tunnel is being constructed by Sound Transit, the area’s transportation agency as part of a roughly $2.6 billion (yep, billion) light-rail project connecting downtown Seattle with the University of Washington and SEA-TAC airport. The voids were a result of running sand pockets in the otherwise stable clay units that were encountered by the tunnel boring machine or TBM. These voids migrated up like a chimney with one reaching the surface, almost 160-ft above the tunnel. This void was apparently 21-ft deep and opened up in a resident’s front yard and could have easily swallowed her up as she noticed it while gardening. The other voids were discovered at a depth of 20- to 65-ft below the ground surface. More after the break. (Illustration from Seattle Times)