TWO ENGINEERS' VIEW OF COST BENEFIT ANALYSIS

Although the use of cost benefit analysis (cba) in highway investment does not result in revenue in the form of cash (except for tolls), highway authorities are required to justify expenditure in terms of community benefit. Hence, economic evaluations are necessary. These attempt to apply standard parameters and values to compare alternative highway solutions. The objective of the exercises discussed in the article is to assess whether the cost of highway improvements is recovered in terms of savings in road user costs and also to optimise design within permissible limits to derive maximum benefit from minimum investment. The authors attempt to measure the benefits of highway schemes using cba by forecasting (1) savings in travel time, (2) savings in vehicle operating costs, (3) savings in accidents prevented, (4) reduction in delay during maintenance operations. In the short term existing techniques to assess traffic benefits will continue to be refined while in the long term electronic systems will be provided to inform drivers of route conditions and suitable diversions where necessary. (TRRL)