THE THEORY AND PRACTICE OF A DUAL CRITERIA ASSIGNMENT MODEL WITH A CONTINUOUSLY DISTRIBUTED VALUE-OF-TIME

A dual criteria assignment model enables an analyst to represent disaggregate trade-offs between two cost criteria in the trip-makers' route choices, eg time and price in the cost vs time model in which a continuously distributed value-of-time (VOT) is assumed. This paper develops the theory and practice of dual criteria assignment. First, the economic background of the model is set out: it enables the analyst to represent various route choice behaviors, variable demand, several user classes, flow-dependent travel time and capacity constraints. Second, the mathematical framework is introduced; due to a special transformation, the model is cast into a variational inequality which under some assumptions reduces to a convex minimisation program. Third, solution algorithms are introduced and compared. Fourth, econometric tools are provided to estimate the distribution of the VOT and to evaluate the uncertainty about the predicted revenue of a toll road, arising from the uncertainty about the distribution of the VOT. It is shown that these tools ensure the practicality of a dual criteria assignment in a medium-sized application. (A) For the covering abstract see IRRD 886400.