Robbins-MHI EPBMs To Excavate Delhi Metro ExtensionRobbins will team up with Mitsubishi Heavy Industries (MHI) to design and manufacture two 6.5 m-diameter earth pressure balance machines (EPBMs) on Phase II of Line 2 of the Delhi metro extension project. The contract, signed on 1st February, 2007 includes the two machines, back-up systems and cutting tools. Robbins will be responsible for the majority of the manufacturing utilizing mainly Mitsubishi designs. Visit www.therobbinscompany.com and www.mhi.co.jp/kobe/mhikobe-e/products/kenki/index.htmlRobbins is getting back into the EPBM market and building on experience of previous EPBM projects that the company has worked on. Robbins has a long association with several international companies and experience on historical soft ground projects such as the Channel tunnel and other projects in the US. The soft ground tunnelling market is expanding, particularly in India and China, and Robbins likes to meet the growing requirements of customers in these countries.The machines will bore parallel 4 km tunnels connecting Udyog Bhawan to Green Park in New Delhi, as part of the BC-16 contract. A joint venture of Continental Engineering Corporation (CEC) and Soma Enterprise were contracted to construct the entire 5.3 kilometres of the new line, which will include four stations excavated by cut and cover, each 318 m long. Click in/11.Delhi Metro Rail Corporation (DMRC), the owner, initiated Phase II to further cut transportation times, particularly when the city hosts the Commonwealth Games in 2010. Phase II of the Delhi metro involves over 53 km of new rail lines at a cost of more than USD1.8 billion. Phase I was recently finished in November 2006, with 65 km of track and 59 stations. An aggressive schedule calls for all civil works to be completed by August 2008 and all tracks to be functional by June 2009 in order to ensure the lines are running well in advance of the games. The EPBMs will bore from 8.6-14 metres below the water table in sandy silt, silty sand and gravels. Both cutterheads feature a 55% opening ratio to allow a smooth flow of muck and to avoid clogging the cutterhead. The machines will use several types of tungsten carbide bits for boring in soft but abrasive ground. Continuously erected lining along the length of the tunnel will consist of reinforced concrete segments 275 mm thick. Both shielded machines are built to withstand pressures up to three bar and feature active articulation for steering. Thrust cylinders automatically maintain their alignments with concrete lining segments even as the heading changes, making tunnel lining more accurate. Muck will be removed using open-gantry, circular back-up systems with single tracks for muck cars to travel down the center. Assembly of the machines will be completed in autumn 2007 and contractors CEC/Soma plan to begin boring in January 2008. 18/07.