Factors influencing trip length characteristics were investigated for the purpose of improving traffic forecasting capabilities. The analysis was based on data obtained from a number of united states and Canadian cities and from computer simulation studies. The three most important factors found to influence trip lengths were ' /1/ size and physical structure of the urban area, /2/ quality of the transportation system, and /3/ socioeconomic factors. The size and physical structure of the urban area, expressed in terms of population and spatial arrangement of activities, have a substantial impact on work, social-recreation, and non-home based trip lengths. The spatial relationships between commercial areas was found to be of great importance in determining shop and truck trip lengths. It was found that peak hour speeds are a key factor in determining work trip lengths. However, most non-work trip lengths are influenced by off-peak speeds. The socioeconomic structure of urban areas was found to be an important element with respect to work and social-recreation travel patterns, but has much less impact on other types of trips. The analyses of the factors influencing work and non-work trip lengths helped to establish various guidelines which can be used for predicting trip lengths and checking travel forecasts. It is concluded that improvements in forecasting procedures are greatly needed. A new distribution model which will take into consideration trip length as well as the spatial distribution of activities within an urban area must be developed.
Abstract