How an individual makes a travel decision under uncertain conditions has been one of the critical issues in designing the information that is delivered by Intelligent Transportation Systems (ITS). This has been a difficult problem because a suitable mathematical framework that deals with the interaction among uncertainty, information, and traveler's attitude toward uncertainty is not available. This paper introduces a possibility theory framework, and demonstrates how this framework represents the uncertainty perceived by the traveler, and calculates the feasibility of achieving the travel objective under different degrees of specificity of information. We present this framework in the setting of selecting the time of departure in the face of a not well-defined desired arrival time and estimated travel time. Feasibility of arrival is measured by the possibility and necessity measures; these measures represent two views, optimistic or conservative, respectively. Anxiety that is associated with the departure time, whether to leave now or not is modeled by Yager's anxiety measures. The anxiety measure considers the conflict of impelling forces between “to leave now” and “not to leave yet”; possibility and necessity measures for these outcomes represent these forces. Thus, along the time axis of possible departure time, possibility and necessity measures of arrival and non-arrival are computed and accordingly, the anxiety measure associated with each departure time. The range of time within which a traveler decides to leave is indicated by the anxiety measure. The size of the range is sensitive to the specificity of information. The more specific the information, the smaller the range of time. While the purpose of this paper is to introduce the mathematical framework useful for the analysis of a traveler's decision under uncertainty, the analysis raises an interesting issue of the paradoxical effects of information accuracy also.
The authors express thanks to Mr. Peter Pilko for preparing the calculation and graphics.
MODEL OF ANXIETY
d1 and d2: alternatives 1 and 2
al and a2: degree of support for alternatives 1 and 2, respectively.
A: anxiety measure [0, 1.0]
In the case of 2 alternatives
Kikuchi, S. and van Zuylen, H.J. (2003), "Modeling of Traveler's Uncertainty and Anxiety", Bell, M.G.H. and Iida, Y. (Ed.) The Network Reliability of Transport, Emerald Group Publishing Limited, pp. 133-154. https://doi.org/10.1108/9781786359544-008Download as .RIS
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