Containing the cost of undergrounding

For many years in the UK, and increasingly abroad, there has been growing pressure for the undergrounding of major overhead lines; the high cost of this has led to a vigorous development of supertension-cable technology. The paper attempts to analyse the value of the many significant advances in cable design and application in reducing the cost of cables relative to that of overhead lines. It concludes that, without these advances, the cost of supertension cables would have been some four times higher than it is. However, simultaneous development of overhead lines, coupled with changes in commercial conditions and cost of materials, have combined to halve the apparent gain from this progress, when expressed as the ratio of the cost of a cable to that of an overhead line of the same rating. In addition, operating experience shows that the reliability of supertension cables is less than that of overhead lines, to an extent that makes this an important factor in such comparisons.