Robbins Breakthroughs in SydneyTwo breakthroughs in two days, on July 27th and 29th, made for an eventful week on the Epping to Chatswood Rail Line project in Sydney, Australia. Thiess-Hochtief Joint Venture (THJV) has now completed 50% of the tunnelling on the project. Tunnelling started at the M2 shaft, which is located approximately in the middle of the 12 km long twin tunnels connecting the two existing rail stations. The Robbins Company supplied the two 7.2 m TBMs, the unique backup systems and a complex conveyor mucking system. The M2 to Epping drives are 6.7 km long, of which 51% is in curves with radii ranging from 500 to 873 m. The TBMs have excavated at rates exceeding 8 m/h. The combination of high muck loads and extremely nonlinear tunnel makes conveying muck one of the biggest project challenges. A concrete roadbed has been cast in place as the tunnel was bored, and all vehicles used are rubber tyred. To simplify logistics and maximize performance, a conveyor system was used to convey muck from the two tunnels, which are 51% curved in the Epping tunnel and 89% in the Chatswood tunnel. A transfer conveyor receives the muck from the two tunnel conveyors, and feeds an incline conveyor to a cable-stayed, radial stacker.The TBMs are currently being turned around to start boring toward Chatswood. Visit www.robbinstbm.com 33/04.