Tunnel Boring Technology

Tunnel boring machines (TBMs) have become an effective alternative to drilling and blasting rock tunnels and have become the only practical means of excavating long tunnels through soft ground and mixed-face conditions. While alternative methods exist for each of the different ground conditions, they are generally more costly and, in many instances, less safe. TBMs have the advantage of being able to mine the ground without disturbing the surrounding ground mass, thereby reducing the potential for instability and eliminating unwanted costs associated with excavating more ground than is required.

Pressurized face tunneling machines would be required for the majority of the tunnel drives. A number of tunnel machine manufacturers have developed tunneling machines that have been used successfully around the world on rail and highway transportation projects.