Mega TBM for Madrid M-30Monday 6th June saw the factory acceptance trials of the world's largest diameter TBM at the Herrenknecht home plant in Schwanau, southern Germany. Leading the client delegation was Dr Manuel Arnaiz Ronda, Director General for Infrastructure for Madrid Calle 30, and currently president of the Spanish Tunnelling Society AETOS. He was accompanied by senior managers of the contracting joint venture Necso / Ferrovial Agroman, who will use the 15.2 m-diameter EPB to bore the EUR331 million, 3.65 km-long 13.45 m ID north tunnel (left carriageway) of the south bypass of the Madrid M-30 project, itself about to become the largest highway project in the world.The TBM will be launched from a 100 m x 60 m-wide x 35 m-deep start box to drive between Paseo de Santa Maria de la Cabeza and the A-3, passing under Vallecas bridge. Crews will work under overburdens of up to 75 m above the tunnel alignment as well as pressures up to 6 bar. The tunnel will open in 2008, relieving considerably traffic on Madrid's city centre and M-30 orbital motorway. The Herrenknecht S-300 TBM features a 7 m-diameter central cutting wheel which can be rotated independently of the 15.2 m-diameter outer cutting wheel, allowing the progressive application of the huge 125,268 kNm of torque to the ground. This would be enough to lift a fully loaded Boeing 747, weighing 410 t, with a 30 m-long lever arm. The central cutting wheel applies a maximum torque of 10,940 kNm. The huge machine has the highest torque ever installed in a TBM. Both cutting wheels can be rotated independently in clockwise and anti-clockwise direction. The total installed main drive power of the outer cutting wheel is 12,000 kW and 2,000 kW for the central cutter wheel. The maximum rotation is 2 rpm for the outer cutting wheel and 3 rpm for the inner cutterhead. The maximum thrust force is 315,880 kN at 400 bar. The outer cutterhead is equipped with 288 bits, 40 double discs and 2 overcutters. The central cutterhead has 84 bits and 16 double discs. The tunnelling giant weighs 4,364 t. For a controlled excavation of the ground and safe support of the tunnel face, three screw conveyors are integrated in the shield. Two large screw conveyors remove spoil from the outer plenum to a conveyor belt in the rear and a third, smaller screw conveyor clears the central cutting wheel. Spoil handling, by screw conveyor and conveyor belt, and segment erection will be the keys to rapid advance in the marly clays of the Madrid Tertiary penuela and gypsum expected enroute. Each 2 m-wide ring of concrete segments will consist of 9 segments plus the key. The machine is currently being disassembled for transport. The superlative TBM is scheduled to go on its journey to Madrid within the next few weeks. Two cargo ships wait to be loaded at the port of Kehl, Germany. They will transport the machine parts and segments to Spain. One cargo ship will navigate to Alicante on the Costa Blanca and the other to Bilbao in the Gulf of Biscay. Even the logistical handling for the subsequent road transport of the machine parts to Madrid is highly demanding. Site assembly is scheduled to start on 1st August, 2005 in the launch shaft in downtown Madrid. Tunnelling is expected to start in October 2005. Visit www.herrenknecht.com and tunnelbuilder archive es/104. 23/05. Factory acceptance of Herrenknecht S-300 TBM for Madrid M-30 project.