Microtunneling

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Microtunneling or microtunnelling is a tunnel construction technique used to construct utility tunnels from approximately 0.5–4 m (1 ft 8 in – 13 ft 1 in) in diameter. Because of their small diameter, it is not possible to have an operator driving the tunneling machine, so they have to be remotely operated.^[1]

Microtunnel boring machines (MTBM) are similar to larger tunnel boring machines (TBMs). The MTBM and jacking frame are set up in a shaft at the required depth. The operator monitors the MTBM's location, orientation and hydraulic devices via a computer console, a CCTV camera or Gyro unit. Some systems use video cameras in the jacking shaft and at the separation plant. Gyro Control have generally replaced cameras for location and digital feedback.