Amec has been awarded a £16.1 million contract to construct a high voltage cable tunnel in Dartford for the National Grid Company. The tunnel length is 2.4 km in length and 3 m internal diameter. It will be driven under the River Thames at depths up to 30 metres through Upper Chalk, Seaford and Lewes formations. Amec will use one of its Lovat TBMs, upsized to 3.5 metre external diameter, operating in earth pressure balance mode. The lining will be precast concrete trapezoidal segments produced and supplied by C V Buchan, a sister Amec business. The segments are 3.35 m external diameter, 1.2 m long, with 6 plates to a ring. Babtie Group are National Grid Company's designers and project supervisors. Tunnelling will start in August 2003 and is programmed to last four months. The contract value includes extensive civil engineering, mechanical and electrical and other works. The project will be financed by the National Grid Company. Visit www.amec.com 14/03.