The design and construction of a 132 kV double circuit line over a route containing extensive uncharted mineworkings

The authors examine the design and construction of a new double circuit 132 kV steel tower overhead line built by the North Western Electricity Board UK, over a 21 km route, to enable a power station to 120 MW capacity to be closed. By necessity the line was built over a route which had been subjected to extensive coal mining activity for a period of 400 years. The mineworking included both charted and uncharted deep shallow and opencast mining. Prior to the new line being built, an existing 132 kV lattice steel tower line in the same area was discovered to have been severely affected by mining subsidence, resulting in reduced ground clearances. The authors also describe the techniques used to refurbish this line, whilst minimising the cost and the period for which the line was out of service