ABSTRACT
The challenging new Metro Barcelona Línea 9 Project where tunnels of up to 10.950 m and 12.060 m diameter are going to be bored under a high-density urban area, is bound to be commenced in spring 2003. Variable and difficult underground conditions will undoubtedly set higher and new standards of quality, safety and schedule meeting in the whole of the construction process: from the TBM technology and the boring process to the ground improving and monitoring. Two EPB shields and one dual hard rock/soil TBM will be used.
