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Data-Oriented Travel Behavior Analysis Based on Probe Person Systems Eiji Hato, University of Tokyo, Japan Ryuichi Kitamura, Kyoto University, Japan P lanning methods, like most methods in science and behavioral aspects, not just trip generation, distribution, engineering, evolve within the confines of the tech- modal split, and network assignment. Examples include nologies available at the time of development, and trip chaining, time use, daily activity scheduling, and travel survey methods are not an exception. It took a leap group behavior. In fact, the last three decades have of conceptualization before roadside surveys, which shown that the information contained in results of con- addressed car trips, were replaced by household travel sur- ventional household travel surveys can be used in ana- veys, which addressed person trips. The conceptualization lyzing a rich spectrum of behavioral aspects as the of urban passenger travel was then formalized to be what is evolution of the activity-based analysis field has demon- known to be four-step procedures. With what now appear strated (Jones et al. 1990, Kitamura 1990). Spatial ele- as extremely limited capabilities of data processing and sta- ments, however, have continued to be the weak link, and tistical analyses in the 1950s and 1960s, the four-step pro- geocoding trip ends to the point in a transportation study cedures adopted the approach of aggregating the rich is rather an exception than a norm even now. Another information available from travel surveys at household and weakness is the error in reporting trip beginning and individual levels to the level of traffic zones. Likewise, trip ending times (Kitamura 1990). ends were coded by using traffic zones. Trip starting and Recent developments in information and communica- ending times reported in the surveys were not well utilized, tions technology, however, are changing this situation by other than perhaps for estimating the duration of each trip, making possible acquisition of precise time and location and many of the analyses in the four-step procedures were information from survey respondents. A Global Posi- performed disregarding the time-of-day dimension. The tioning System (GPS) unit integrated into a cellular problem today is that many of these weaknesses remain, phone transforms a survey respondent into a "probe" when many of the technical constraints have disappeared. (subsequently called "probe person" rather than "probe Researchers became aware of the statistical ineffi- vehicle") whose trajectories in space and time can be ciency of aggregating information to the zone level as recorded with levels of accuracy unimaginable from the early as the 1960s, and estimation of trip generation conventional questionnaire-based surveys. When these models at the level of household was proposed. At the are supplemented with web-based data acquisition on time, however, storing and processing of data were quite the contents of activities (what type, with whom, etc.), a challenge. Fast computers, inexpensive data storage opportunity characteristics (facility types), and trip media, and easy-to-use statistical and econometric soft- attributes (cotravelers, parking facilities and charges), ware packages now available have made the analysis of one can obtain every type of measurement that has tra- large-scale household travel survey results possible at the ditionally been used in travel behavior analysis and desktop of a researcher or planner. Household travel sur- demand forecasting. In addition, attempts have been vey results have been used to analyze a wide range of made to acquire unconventional measurements, such as 187