§ Mr. GrahamTo ask the Secretary of State for Scotland what criteria are used to decide whether any part of a motorway in Scotland should be provided with lighting.
§ Lord James Douglas-HamiltonLighting on motorways is normally provided when cost benefit calculations show that the benefits of a reduction in the number of night-time injury accidents would exceed the cost of its installation and subsequent maintenance. White-lining, cats' eyes and other markings are considered adequate in ordinary circumstances and generally, on motorways, lighting would afford only marginal road safety benefits which would not justify the cost.
The detailed criteria are set out in the Scottish Office Technical Memorandum SH6/89 ("Appraisal of New and Replacement Lighting on Trunk Roads and Trunk Road Motorways"), a copy of which I am arranging to be placed in the Library.