POWERING UNDER LONDON

Three Lovat TBMs have been digging a 20-km course beneath the northern suburbs of London for the past year. The tunnel is the London Connection Project, which will carry electricity between two substations with a 400 kV cable, which will ramp up capacity to meet growing electrical demand. The tunnel is designed to have capacity for a second electrical cable within 10 to 15 years. Overhead power lines were dismissed for the heavily residential area, and digging up the roads in the region was considered too disruptive. The project is divided into three segments with six shafts. It passes through seven different formations. Tunneling began in September 2001. The contractor used a larger ring than usual, 1200 mm, to increase the daily advance, which has resulted in 20% higher production rates and suits the long travel times between the shaft and face in this project. The tunneling is nearing completion, which will leave the contractor the job of fitting out the shaft, completing the shaft headhouse buildings and other mechanical and electrical elements. It should be handed over to the utility by end of summer 2003.