NFM Technologies TBM Breaks Through Green Heart Tunnel in the NetherlandsThe biggest diameter TBM ever built in the world, 14.87 m in diameter with a weight of 3,520 tons, broke through ahead of schedule the 7,176 m-long Green Heart (Groene Hart) tunnel on 17th January in the presence of Dutch minister for public works and water Mrs Karla Peijs. The Green Heart high speed rail tunnel connects Hoogmade with Hazerswoude-Dorp, on the Amsterdam-Rotterdam rail link. With its cut-and-cover access ramps, the tunnel will be 8 km in length.The contracting JV, including Bouygues and Dutch partner the Koop Holding Europe, used a 120 m-long NFM Technologies slurry shield machine, named 'Aurora', to drive through peat, clay and saturated sand. The machine has an installed capacity of 8,000 kVA and a total thrust of 184,300 kN. The cutting head rotated at a speed of 0-1.4 rpm. The TBM is 10% larger than the previous record (14.2 m in diameter). It is equipped with the Benton'air® slurry pressure confinement technology consisting of bentonite slurry pressure applied on the face with air bubble regulation. It started its job on 2nd November, 2001 from the Bospolder excavating a 176 sq m cross section. The job was completed earlier than the initial objective set for next spring thanks to a 12-16 m daily average advance instead of the planned 9-12 m, with a best month of 616 m (106,980 cubic metres). The lining concrete rings are formed by ten segments. In total, 35,870 segments have been installed. A total of 1.3 million cubic metres of spoil has been removed. The machine has been sold to Shanghai Tunnel Engineering Co. (STEC). Visit www.stec.netThe tunnel will put Amsterdam just 35 minutes away from Rotterdam. Trains will start operating between Amsterdam and Paris via Antwerpen and Brussels in April 2007, cutting travel time to just two hours.Visit www.hslzuid.info, www.nfm-technologies.com, www.bouygues-construction.com and www.koop.nl 05/04.