Scheduling of Interstate Road and Railway Investments

Abstract

If investment activities are restricted by binding budget constraints, it may be even more important to find a good time schedule for investments rather than to determine the optimal investment program for a future time period. The problem of scheduling investments for interstate road and railway investments can be formulated as a mixed-integer programming model. But this model is so large, that it is hopeless to try to solve problems of practical relevance. For this reason two ways of simplifying the problem are discussed. The first method focuses on modelling of budget feasibilities over time, and the second method stresses the interdependencies of network improvements. As these interdependencies are predominantly affected by the interrelationships between network structure and travel flow pattern, it is important to model travel demand for competing transportation modes in a sufficiently precise way. An algorithm for combined two-mode modal choice and travel assignment is presented which generates the changes in travel demand affected by a change in the network structure in an efficient way. A test network is used to illustrate the computations and the efficiency of the methods presented.