20. Guidelines for the routeing of new overhead lines were originally formulated by the Central Electricity Generating Board (CEGB), a predecessor to National Grid. These guidelines have subsequently been reviewed and supplemented by National Grid and are used as the basis of the company’s approach to routeing new overhead lines.

21. The guidelines set out the principles to be applied in the routeing of new overhead lines. They cannot be expected to cover every possible situation and each case must be considered separately and on its own merits.

22. The selection of any new electricity line route will be a balance of all the various factors or constraints which have to be taken into account. Any overhead line will be a visual intrusion into the landscape through which it passes, and it is the dominant scale of pylons which makes them difficult to absorb into the landscape.

23. In selecting a route National Grid seeks to reduce the visual effect of the line in terms of the number of people affected and the degree to which they are affected. The nature and topography of the landscape is considered and any statutory protection afforded to an area is also taken into account.

24. The selected route will typically seek to avoid crossing the highest contours, where pylons would generally be the most prominent and will take account of the quality of the landscape and its ability to accommodate an overhead line. In other words an overhead line should ‘fit’ into the landscape as much as that landscape permits. The extent to which opportunities exist to screen the line will depend on existing vegetation, buildings and topographic features. When viewed from principal viewpoints, an overhead line should ideally be viewed against a background of existing landscape or other development rather than against the sky.

25. There may be a number of potential conflicts of interest in establishing a new overhead line route. Sometimes, for example, the best route through a landscape will be to follow a river valley rather than to cross the adjacent higher land. The valley, however, is likely to be more intensively populated and also may contain the major transport routes in the area as well as the better quality agricultural land. A new line so routed could have a greater effect on a larger number of people even though its effect outside the valley may be minimal. Conversely for example, upland areas, whilst having relatively little development, are likely to have protective designations and an overhead line across such areas may be visible over a much wider area.

26. These are all general routeing principles. In practice, the selection of a route will very much depend on the circumstances applicable to each case.