This is an interesting video of crews changing cutterhead teeth on the Bertha TBM beneath downtown Seattle. [Source: WSDOT YouTube Channel. Image: YouTube]
Video: Changing cutting tools on Bertha TBM
Miscellaneous
Insights on the tunnel design industry and a profile of Brierly Associates
The August 2011 issue of Tunnel Boring Magazine contains a profile on Brierley Associates, an engineering firm specializing in tunnel design based in the Denver, Colorado area. The article provides some nice insight into the […]
Project Related
Alleghenny Tunnel Nearing Completion but Hurting for Money
Pittsburgh’s light rail expansion project dubbed the North Shore Connector Project has passed underneath the Allegheny River despite some earlier troubles. The cut and cover tunnel portion is complete, and the TBM bored portion of […]
Project Related
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)