Installing the the 'mole' for its 7 km journey boring out the tunnel for the SPS

The mole being installed underground at the point where boring of the tunnel had begun. The mole had a 7 km journey confronting it around the circumference of the ring which was expected to be completed by Autumn 1974. The head shown was 4.8 m in diameter. It was lowered into the tunnel in January and the whole machine was assembled below ground. In addition to the head, the machine comprised pressure and supporting pads, an operator's cabin, electrical equipment, conveyor belts, tunnel lining system, skip changer and spoil removal train. Its total length was 80 m.