The Boring Company’s tunnel boring machine is nearly complete with the first half of the dual tunnel people mover system servicing the Las Vegas Convention Center. The secretive tunnel project is reported to cost $52.5M and feature self-driving vehicles utilizing the Tesla chassis. The largest vehicle will fit 16 people and multiple vehicles can be platooned to load and travel together much like a conventional light rail or subway system but without the connections. Once the TBM finished the first bore, it will be disassembled and brought back to the starting point to excavate the second tunnel. The entire project is supposed to be online for the 2021 Consumer Electronics Show (CES).
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)