Temporal Comparison of Discretionary Trip Generation Model Considering the Mutual Relationship between Week and Weekend Days

In recent years, travel patterns have been diversified due to the tempo-spatial changes of city structures or traveler characteristics caused by the rapid development of motorization, suburbanization, etc., and yet at the same time in transportation demand modeling, more accurate analysis by considering these changes of socio-economic structure is required.Furthermore, many conventional urban transportation planning were drawn up mainly in consideration of commuting trips or business trips, which are typical and undertaken only on weekdays. However, recently with changes in lifestyle or increase in leisure time, the trip generation for discretionary activities such as shopping, leisure, etc. has risen, and then various traffic problems are stressed especially on weekend. In spite of increasing the importance in formulating prediction model for discretionary trips on weekend, the previous researches including those on weekdays are not necessary enough and it can be said that more detailed analysis is still sorely needed.This study mainly focuses on the urban travel behavior on weekdays and weekend, and aims to build a model of trip generation for discretionary trips. After examining the actual condition of discretionary trips, it hypothesizes that there is a common factor which affects the generation of discretionary trips performed on both weekdays and weekend, and that weekday and weekend trips are mutually influenced. Then, by applying a covariance structural model it examines the hypothesis and estimates the effects of various factors on the generation of discretionary trips. Finally, temporal structural comparisons of trip generation between two points in time are examined and discussed.As a result, statistical results suggest that there is a common factor which affects travel behavior on weekdays and weekend as well as factor which is specific to either weekdays or weekend. In ten years from 1991 to 2001, weekday and weekend discretionary trips had become less dependent on the common factor. It was also found that effects of weekend constrained trips on the generation of discretionary trips are significant especially on weekend.JEL classification: Mathematical and Quantitative Methods