For the Hudson Tunnel project, which will create new railway tunnels between New York and New Jersey, two massive Tunnel Boring Machines (TBMs) will play a key role. These advanced machines are designed to excavate medium to large tunnels, even under challenging underwater conditions
However, TBMs are only one of several techniques used to build railway tunnels. Let’s explore some of the other methods employed in tunnel construction.
Drill & Blast
The most widely used mining extraction method in the world begins by drilling into the rock. The holes are then loaded with explosives that cause the rock to fracture and break apart.
Cut and Cover
This technique is mainly used for shallow tunnels, such as those in metro systems. A trench is dug, and then it is covered with structures capable of supporting heavy loads.
Clay Jacking
An older method, primarily used for smaller projects like installing drainage pipes. A pit is dug, and then a tunnel is created with clay. It’s notable because British engineers used it to place mines under German lines during World War I.
Shaft Method
Used for constructing deeper tunnels, this involves creating a permanent shaft-like structure down to the required depth. TBMs are then used to excavate the tunnel.
Pipe Jacking
This technique is used to build tunnels beneath roads and railways. Pipes are pushed underground using hydraulic lifting systems.
Box Jacking
Similar to Pipe Jacking, but instead of pipes, special boxes are inserted into the ground. A cutting head at the front of the box cuts the soil, and the excavated material is collected inside.
