Teamwork Tunnelling: It's moving in Madrid's underground.
Spain is currently one of the world?s busiest arenas for powerful TBM giants. 18 Herrenknecht large-diameter tunnelling systems are part of regional and trans-regional Traffic Tunnelling projects. November 2005 saw the launch of what is currently the world?s largest tunnel boring machine (excavation diameter 15.20m) in Madrid. The Herrenknecht S-300 Earth Pressure Balance Shield is set to drive the 3.65km underground freeway north tunnel of the ?M-30? in the middle of the capital. With 125,268kNm the machine has the highest torque ever installed on a TBM.
In order to maintain control of the large excavation diameter in high friction ground conditions Herrenknecht engineers have come up with a specially developed and unique cutting wheel concept for this project. It consists of an inner cutting wheel with a diameter of 7m and an outer cutting wheel (diameter 15.20m) working on the same plane. Week by week the giant boring machine knows to convince with increasing performance rates. By mid-February 2006 the contractors? construction team (Acciona Infraestructuras S.A., Ferrovial-Agroman S.A.) already constructed 600m of tunnel (300 rings) with the help of the giant. The best daily performance was 22m (11 rings).
Regular as a Swiss clockwork another high-tech boring machine (S-299) from Schwanau bored ahead in the clayey and sandy ground of the Spanish capital. The EPB-Shield (ΓΈ 9.37m) already reached its target on December 7th, 2005 after an excavation period of only six months and 2,600m of completed tunnel. The new tunnel section in downtown Madrid was driven with best weekly performances of 196.5m (131 rings).
Since its launch the ?twin machine? (S-302) has really been pushing ahead. On its way through lime, sand and loam the machine advances with the 3,600 kilowatt cutting wheel achieving best performances of 48m per day (32 rings) and up to 244.5m per week (160 rings). These top performances have so far been unparalleled compared with advance rates of TBMs with similar parameters in terms of dimension and power.
Overall eight Earth Pressure Balance Shields from Schwanau pave the way for new metro lines deep under the Spanish capital. Week by week the machines construct up to 1,000m of tunnel in the underground; This indicates the rapid development of the metro system. 52 kilometers of the system were completed between 1999 and 2003. Another 72 kilometers are scheduled for completion by 2007. Today Madrid?s metro system is already the third largest in Europe - after London and Moscow.
