The Temporal Stability of Trip Generation Relationships : Technical Paper

Abstract

Trip generation models based on household data rather than zonal aggregate data are evaluated. It has been suggested that analysis of household travel characteristics should precede aggregation so that home interview data can be used more efficiently. Relationships identified at the decision level of travel should have greater causal validity and should be more temporally and spatially stable. The major objectives of this research are to examine the form of household travel relationships, to determine the stability of these relationships over time and to evaluate the ability of household models to estimate future travel. The potential for reduced sample size requirements and greater applicability of disaggregate models in different urban areas are also examined. To examine the stability of disaggregate trip generation models, household travel data were obtained from home interview surveys in 1964 and 1971. Single family households interviewed in the 1971 survey represented the identical families which were interviewed in 1964. This unique sampling design permitted the analysis of the effects which changes in the households' socioeconomic characteristics during the seven year period have on trip production. The results indicated that the household models based on the 1964 data could successfully predict household travel reported by the same households in 1971. The household models from both time periods could be expanded to adequately estimate 1964 reported zonal area travel. Parameters of the disaggregate models also appear more consistent between geographical areas and could be developed with considerably less data than comparable zonal models,