Embedding Risk Attitudes in a Scheduling Model: Application to the Study of Commuting Departure Time
In traditional travel time reliability valuation studies, the value of travel time savings and the value of travel time reliability (or reduced time variability) are estimated within a linear utility functional form, which assumes risk-neutral attitudes for decision makers. In this paper, we develop nonlinear scheduling models to address both risk attitude and preference in the context of a stated choice experiment of car commuters facing risky choices where the risk is associated with the trip time. We also investigate unobserved between-individual heterogeneity in time-related parameters and risk attitudes using a mixed multinomial logit model. The willingness-to-pay values for reducing the mean travel time and variability (earlier/later than the preferred arrival time) are also estimated within the nonlinear scheduling framework. The model is then used to estimate preferred departure times for commuters, assuming that random link capacities are the source of travel time variability. Results show that the more variable travel times are, the earlier commuters depart and that the nonlinear scheduling model predicts earlier optimal departure times than the linear scheduling model does. The application in this paper helps to bridge the gap between theory and practice.
Identifying commuter preferences for existing modes and a proposed metro
In 2009, the New South Wales government announced that it would be proceeding with a feasibility study to identify the patronage potential of a new Metro rail system for Sydney. As part of this study, a new modal choice study was undertaken to establish the role of traditional attributes such as travel times and costs (and more recently, reliability) but also somewhat neglected influences such as crowding, where the later has a critical role in the calculation of capacity needs at railway stations. This paper focuses on the commuter segment and develops a new stated choice experiment in which travellers are able to compare the proposed new Metro with existing available modal alternatives for access, linehaul and egress trip stages, with a particular emphasis on the incorporation of crowding represented by the availability of a seat vs. standing in existing and new public transport modes. We present the error component choice model together with estimates of mode-specific willingness to pay for travel time components, service frequency and crowding, that latter expressed in terms of the probability of getting a seat and the probability of avoiding standing.
