Exponential Disutility Functions in Transportation Problems: A New Theoretical Justification ?

In modeling drivers’ route choice in stochastic networks, several researchers havesuccessfully used exponential disutility functions. A usual justification for thesefunctions is that they are consistent with common sense and that they lead tosimpler computations than several other alternative disutility functions. In principle,such a justification leaves open a possibility that there is some other (yet un-tried)disutility function which is also consistent with common sense and for which thecomputations are even simpler than for the exponential function. In this paper,we prove that exponential disutility functions are the only ones that are consistentwith the (appropriately formalized) common sense and the only ones for whichcomputations can be simplified.