Abstract
Road schemes with and without improvements are evaluated by means of a computer program (C.O.B.A.). The existing traffic flow is measured in terms of its principal components and is estimated for 30 years ahead of the road's proposed opening date. The benefits of the scheme are then calculated by subtracting the cost of using the road with new improvement from that of using it without the improvement. Most of the benefits are attributed to time savings. It is concluded that the present framework for evaluating road schemes may not be satisfactory.