An important but often neglected problem in the analysis of transportation systems is the allocation of funds to improve the network. The use of traffic assignment procedures represents one means of finding the minimum total travel cost to distributing traffic in a transportation network. The problem of investment may be separately formulated as that of either increasing arc capacity or decreasing unit travel cost. Assuming that there is a given saving in unit travel cost on an arc for each unit of investment in that arc, the problem is how to allocate the budget to produce the greatest reduction in minimum total travel cost. The initial assignment of traffic suggests which arcs should receive investment. However, as the investment proceeds, the assignment of traffic changes. With a large network the number of assignment and investment possibilities produces a complex combinatorial problem. A special case is the shortest route problem, which is the focus of this paper. An algorithm is proposed for investment to reduce the shortest route that is an extension of a shortest route algorithm.
Abstract