Space-time accessibility under conditions of uncertain travel times: Theory and numerical simulations

Recently, several accessibility measures using the space-time prism concept have been suggested in the literature. These measures fail to take into account (i) the ability of individuals to adjust their activity-travel patterns in coping with constrained choice sets, (ii) uncertainty in the perception of travel times, (iii) temporal variability of travel times, and (iv) the influence of travel information on accessibility. The aim of the present article is to contribute to this literature by addressing these four shortcomings. Theory will be developed and illustrated using numerical simulations. The results suggest that the accessibility measure proposed in this article is a useful indicator of social inclusion in terms of the time individuals can spend to conduct their preferred activities. Moreover, accessibility is found to be affected by the presence of schedule delay penalties, restrictions in time allocation to activities, and the provision of travel time information in order to reduce uncertainty.