§ 16. Mr. Cartwright
asked the Secretary of State for Transport whether he intends to review the distribution of responsibility for major roads between his Department and local authorities.
§ 43. Mr. Coombs
asked the Secretary of State for Transport how he estimates the costs and benefits of road schemes carried out by his Department.
§ Mr. Peter Bottomley
The estimates are based on a comparison between the scheme itself and an alternative "minimum improvement" option. The value of future benefits from reducing journey times, decreases in the number and severity of accidents and savings in vehicle operating costs is estimated and compared with the extra capital and maintenance costs involved. A 30-year life is assumed for appraisal purposes and all costs and benefits are discounted at 7 per cent. per annum to provide a net present value estimate for the scheme.
It is estimated that an average trunk road scheme provides about £1.50 of the discounted future benefits for every £1 spent on its construction. This is broadly equivalent to an internal rate of return of 12 per cent.