A Moment of Time: Reliability in Route Choice Using Stated Preference

Abstract

Understanding how reliability is valued is important because it provides insight into how aims of policies that aspire to provide better transport options can be more fully integrated with user expectations. Better reliability is a desired outcome of transportation policies because it reduces scheduling costs. This study uses a stated preference survey to collect route preference data, in which each route is described by the travel time experience on it. Because travel-time decisions are made from momentary recollections of past experience, the paradigm adopted in this study is that the mode travel time rather than the mean is the important basis for travel time decisions. The authors then explore three alternate measures of reliability and use them to estimate route choice models on the basis of the stated preference data. Two of the measures, range coupled with lateness probability and standard deviation, have been explored before. A third measure based on time moment (moments of inertia) measured from the mode travel time is also proposed and tested. Each measure reveals something different about how people value different aspects of reliability. In all cases, reliability is valued highly, although differently depending on how it is defined. The values of reliability and travel time highlight that transportation policy makers can provide significant benefits to users from strategies that seek to increase reliability.

Keywords:

• travel-time reliability
• reliability ratio
• value of reliability
• unexpected delay
• unexpected early
• mode travel time

Notes

^aValue of reliability (per hour decrease in the average lateness).

^bValue of reliability (per hour decrease in right range).

^cValue of reliability (per percentage point change in lateness probability).

^dValue of reliability (per hour decrease in the standard deviation).