Space-time user benefit and utility accessibility measures for individual activity schedules

Accessibility is a fundamental concept in human existence, which goes to the heart of the notion of society, equity, and justice. However, despite the importance of the concept, the mathematical measures that have historically been used to quantify accessibility levels have been relatively poorly defined and have encompassed a limited range of observed forms of travel behavior. Existing space-time locational benefit measures are extended to encapsulate more realistic temporal constraints on activity participation and the associated perceived user benefit. The development of a family of space-time route benefit measures is outlined. Despite their apparent theoretical attractiveness, hitherto researchers have not used such measures. It is demonstrated how these route benefit measures can be used to develop an associated family of disaggregate activity-based space-time utility accessibility measures applicable to individual activity schedules and how income constraints can be incorporated within the space-time utility accessibility measures. Finally, the means by which stochastic frontier models can be used in conjunction with existing travel-activity diary data sets to operationalize the proposed measure of accessibility are briefly described.