asked the Secretary of State for Transport what evidence exists on the cost-effectiveness of the lighting of trunk roads and motorways; and if he will explain the method of cost-benefit analysis applied to assessing the cost-effectiveness of such lighting.
When new or improved lighting is proposed for a trunk road or motorway, a full cost benefit analysis is undertaken to demonstrate that it is worthwhile. The evidence for the expected benefits from the saving in accidents is derived from Transport and Road Research Laboratory studies, which support the claim of approximately 30 per cent. night-time accident savings for road lighting.The method for the analysis is set out in the departmental advice note TA 49/86, a copy of which is in the Library.Where lighting is replaced to a similar standard there is no likely improvement to the night accident situation —for example, where a lighting system at the end of its useful life is replaced. Then a cost effective approach is adopted to identify the least whole-life cost solution.