Measuring joint space-time accessibility in transit network under travel time uncertainty

Abstract

In densely populated areas, joint activity participation such as shopping and eating outside represents a substantial portion of individuals' daily activity-travel patterns. Individuals have several considerations in making joint activity choice behaviour such as space-time coordination, activity start time, activity location and joint activity duration. In a congested transit network, the travel time uncertainty significantly affects individuals' activity and travel choice behaviour. To conduct some important joint activities, individuals normally have high expectations of on-time arrival. Thus, the measurement of space-time accessibility in transportation networks should be extended to consider joint activity choices and travel time uncertainty. In this paper, a new method for measuring space-time accessibility is proposed for individuals' joint activities in transit network with consideration of travel time uncertainty. A reliable alighting location model is proposed to identify all feasible alighting locations in transit network to perform joint activities by explicitly considering constraints of on-time arrival probabilities. Individuals’ joint space-time accessibility (JSTA) is measured based on reliable alighting locations, travel time budget, and points of interests. Massive smart card data from metro network in Nanjing, China are used to show the merits of the proposed JSTA measure. The results show that there is a significant difference between the space-time accessibility to independent activity and that to joint activity under various on-time arrival probabilities. The effects of spatial (de)concentration of anchor locations and minimum joint activity duration on JSTA, and the role of additional participants are also presented in various scenarios. The proposed JSTA measure can be used to help policy makers to evaluate transit network development and land use planning in urban areas.