ABSTRACT
Pipe Jacking Machine and Tunnel Boring Machine share the same objective, to go underground by intensive use of mechanized tunnelling solutions. The two systems have their well-known elective field of application, and the boundary can be defined around a 3m external diameter where a Pipe Jacking pushing system can still manage the advance if tunnel is straight, not too long, in a quite simple geotechnical condition, and there is enough space inside to organize all the equipment that must enter the tunnel if a TBM is used. But more and more, the request of pipejacking is moving forward to conditions where they are somehow at the limit, because the advantages of this technique are still appreciated and required, for the short time of mobilization and the limited works required on surface to start the tunnel excavation. The industry is intercepting this need and is trying to give an answer.
