Disaggregate Travel and Mobility-Choice Models and Measures of Accessibility

Existing measures of accessibility are not based on an explicit behavioural theory. This chapter proposes an accessibility measure which is consistent with the application of random-utility models to individuals' decision processes. The proposed measure is the expected maximum utility that a consumer derives from a given situation. The chapter presents the properties and advantages of this measure and its derivation for the special cases of the multinomial logit and probit choice models. Given the multidimensional nature of the travel and mobility choices, this measure is also shown to provide a logically consistent linkage between component models in a complete model system of travel and mobility choices. The use of this measure is demonstrated for joint and sequential logit models. Finally, the chapter addresses key problem areas in the state-of-the-art of spatial-choice modelling which directly affect the development of measures of accessibility defined over a large set of spatial alternatives.