There are a wide variety of special transportation services targeted to the elderly and handicapped. The demand for trips on these services vary greatly. In expanding these services or designing new ones, planners need to have accurate estimates of demand. However, the usual method of demand analysis for special services is based on estimating the size of the target population and multiplying it by an assumed trip rate taken either from a survey of the target population or from a similar system in another locale. An implicit assumption is that the characteristics of the actual service to be provided have little impact on its use. Not surprisingly, the demand that develops for the actual system often has little relation to the pre-implementation estimate. In order to improve demand analysis for special services, the effects of the pertinent causal factors need to be incorporated into the analysis. These include the characteristics of the target population, fare, marketing, other available transportation, and the quality of the service. Many characteristics of service contribute to quality, such as reliability, safety, and comfort. Because including them all is not feasible in demand analysis, finding a way to reduce the number of separate variables is necessary. One approach is to develop a comprehensive measure to represent quality. The purpose of this paper is to describe such a measure or index of quality and how it was derived from a ranking by users of special service.(a) for the covering abstract of the conference see IRRD 290118.
Abstract