Courtesy WSDOT Operators monitor progress from Bertha's control room. Courtesy WSDOT Largest TBM in North America, measuring 57.5 ft in dia, is temporarily stuck along its 1.7-mile underground course. Related Links: Big Tunneler Headed For New State Route 99 Site People Dig Tunnel Boring Machines That Tweet Joint-venture contractor Seattle Tunnel Partners needs divers to enter the chamber behind a tunnel-boring machine’s cutting head to investigate what possibly slowed—and subsequently forced a shutdown of—North America’s largest TBM, nicknamed "Bertha." The 57.5-ft-dia TBM is attempting to bore a 1.7-mile Alaskan Way Viaduct replacement under downtown Seattle. On Friday, Dec. 6, Bertha, which
The market is generally healthy and steadily growing, and margins are up for large specialty contractors. Further, advances in design tools and owner demand for collaboration are giving subcontractors a seat at the table early on in projects.