Pipe ramming

Distances of 30 m (150 feet) or more and over 500 mm (20 inches) in diameter are common, although the method can be used for much longer and larger installations.

Pipe ramming is preferable for shorter distances and applications that do not require tight directional control, such as cable installations.

Further reduction of friction is typically achieved with lubrication, and different types of bentonite and/or polymers can be used (as in horizontal directional boring) for this purpose.

[citation needed] The alignment is controlled using a laser beam from the launch shaft, which guides the machine through the tunnel axis.

The laser beam is directed to the machine cutter head and its position is controlled in real time by a navigation system at the surface.