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BREAKOUT SESSION Survey Methods Eric Petersen, RAND Europe Peter Vovsha, PB Consult, Inc. Stacey Bricka, NuStats Partners, LP Chandra Bhat, University of Texas at Austin Bruno Kochan, Transportation Research Institute, Hasselt University, Belgium Tom Bellemans, Transportation Research Institute, Hasselt University, Belgium Davy Janssens, Transportation Research Institute, Hasselt University, Belgium Geert Wets, Transportation Research Institute, Hasselt University, Belgium DIRECTIONS FOR COORDINATED IMPROVEMENT veys. Trips represent the unit of analysis in traditional OF TRAVEL SURVEYS AND MODELS four-step models. The units of analysis in activity-based models include trips, tours, activity episodes, and time Eric Petersen and Peter Vovsha allocation. Household surveys were conducted as part of the Peter Vovsha discussed data requirements to support the development of new activity-based models in New York, estimation process of activity-based models and Columbus, Atlanta, and the San Francisco Bay area. The improvements to travel surveys. He described the New York survey included approximately 11,000 house- demands of the new models and promising areas of holds in a 1-day survey. The Columbus survey was also research related to travel surveys. Volume 2 includes a a 1-day effort involving 5,555 households. Two-day sur- paper on the topic.1 The following points were covered veys were conducted in both the San Francisco Bay area in his presentation. and Atlanta, covering 15,064 households and 8,069 households, respectively. A review of these surveys iden- Household travel surveys remain the major source tified concerns related to missing and miscoded loca- of data needed for activity-based models. The basic sur- tions, in-home activities, conflicting joint activities and veys required for activity-based modeling applications travel, underreporting of multiple activities, underre- are similar to those required to update and revalidate porting of nonmandatory activities, and underreporting conventional models, although some additions are desir- of preschool children. One example of underreporting able. The development of the new generation of activity- relates to the percentage of workers making at-work sub- based models has provided the opportunity to examine tours for lunch, banking, shopping, and business the various types of travel surveys. This examination has activities. identified some data inconsistency not previously noted. Conducting on-the-spot checks represents one The development of new models has also created approach to improving household survey results. Items demands for new data and possible changes to travel sur- to check include consistent trip time locations and modes and consistent departure and arrival times. Joint travel by drivers and passengers can be checked for intrahouse- 1 See Petersen E., and P. Vovsha. Directions for Coordinated hold trip synchronization and interhousehold trips with Improvement of Travel Surveys and Models. In Conference Proceedings 42: Innovations in Travel Demand Modeling, Volume 2: colleagues, friends, relatives, and casual carpoolers. Joint Papers, Transportation Research Board of the National Academies, intrahousehold and interhousehold synchronization can Washington, D.C., 2008, pp. 8588. also be monitored. The presence of routine activities 33