World Record for Hard Rock Shield TBM Advance at La Cabrera TunnelConstruction of the La Cabrera tunnel on the Siete Aguas-Buñol section of the high speed line Madrid-Castilla La Mancha-Valencian Community-Murcia Region is underway by a joint venture of FCC and Sando Construcciones, on behalf of ADIF, the high speed railway authority under the Ministry of development. The JV has set a new world record for advance rate at the La Cabrera tunnel. The tunnel is one of the most and complex structures on the future line. A 9.6 m-diameter double shield hard rock TBM from Herrenknecht installs the precast segmental ring lining as it progresses. Visit www.herrenknecht.com, www.fcc.es, www.sando.net and www.adif.es The machine has already beaten four times the world record of advance in its category. Last 27th September, 2007 crews achieved a daily advance rate of 65.6 m of tunnel fully lined with 41 segmental rings. Last 1st October, they even improved that figure and established what is believed to be a new world record, with 67.2 metres of tunnel and 42 segmental rings. . In November, the advance progressed further to 72 metres (45 rings) and on 25th November, it even reached 80 metres (50 rings). The TBM has a maximum advance capacity of 1.60 metres every 20 minutes. The average speed at which it bores, 10 centimetres per hour, will enable crews to finish the twin tunnels in December 2008, four months ahead of schedule. For a complete list of world records for TBM advance rates, visit www.therobbinscompany.comThe 7.250 m-long La Cabrera tunnel is the longest tunnel on the 914 km high speed line. It crosses the Sierra de La Cabrera. The TBM began to excavate the left bore last 27th July and it has already completed more than 2,000 metres. Click here. It is expected to excavate the remaining 5.5 km at the same pace prior to start the right tube.The La Cabrera tunnel consists of two parallel tubes, of 8.75 m inner diameter. It is excavated in carbonated rocky materials (limestone, dolomites, marly limestone, etc.). Both tunnels are cross-connected each 400 metres. These cross passages are built simultaneously with the construction of the main tunnel.The double shield TBM carries out simultaneously the synchronized excavation and the placement of the precast concrete rings made of seven segments fastened together to form the lining rings. Each segment is approximately 1.6 m wide and weights 8.5 tonnes. They are fastened by means of connectors and screws. The TBM is 200 m long and weighs 2,400 tonnes. Each shift has 24 people and works takes place 24 hours. 48/07.