Robbins TBMs progress longest direct tunnelAt India's remote AMR water tunnel, on 18.06.2011, the 10.0 m-diameter Double Shield Robbins TBM at the inlet end was launched. Launch was severely delayed following a monsoon flood that breached the coffer dam wall protecting the launch excavation and inundated the machine with 20 m of water. Following an extensive rebuild, the TBM has now bored 20 m to allow installation of all back-up gantries and auxiliary equipment.The identical machine boring at the outlet end of the tunnel has reached the 10 km mark and is now undergoing cutterhead maintenance and refurbishment. This TBM achieved rates of up to 512 m/month in the highly abrasive and blocky ground, consisting of granites up to 230 MPa UCS. The 43.5 km-long AMR water tunnel will be the longest tunnel in the world driven by TBM without intermediate access. The project is part of a massive 120 km scheme by the Andhra Pradesh Irrigation Department to assuage chronic drought conditions and contaminated drinking water. The tunnels are sourced at the Srisailam Dam on the River Krishna. Read the press release. For more click here and in/45. Visit www.robbinstbm.com. 31/11. Launch of the Robbins Double Shield at the inlet portal of India's AMR water tunnel