The process of activity scheduling is crucial to the understanding of travel behavior changes. A new computer program, REACT!,has been developed to collect household activity scheduling data for this purpose. The program is implemented as a stand-alone program with Internet connectivity for remote data transmission. It also contains a GIS for location identification and a special feature that traces the decisions in the scheduling process. A pilot study was conducted in Irvine, California, to evaluate the program performance. Preliminary analysis validated the program's capability of guiding participants to complete data entry tasks on their own, thus achieving the objective of reducing the cost and human resource associated with such a computerized survey. Other positive results regarding objectives of reducing instrumental biases and expanding program capabilities were also obtained. Areas for improvement were also identified in the pilot. Based on the finding, REACT! represents an ideal platform for a computerized household survey that can produce data for activity-based travel models.

Understanding the process of activity scheduling is a critical prerequisite to an understanding changes in travel behavior. To examine this process, a web-based activity survey program, REACT!, was developed to collect household activity scheduling data. REACT! is unique in that it records the evolution of activity schedules from intentions to final outcomes for a multi-day period. This paper summarizes an investigation of the structure of activity/travel patterns based on a REACT! data set from a pilot study conducted in Irvine, California. The term structure refers to the outcome of a set of decisions facing individuals as they conduct their daily activities. At a minimum, structure can be interpreted as the sequence by which various activities enter one's daily activity scheduling process. Results of the empirical analyses show that activities of shorter duration were more likely to be opportunistically inserted in a schedule already anchored by longer duration counterparts. Additionally, analysis of tour structure reveals that many trip-chains were formed opportunistically. Travel time required to reach an activity was also positively related to the scheduling horizon for the activity, with more distant stops being planned earlier than closer locations.

This two-year project focused on obtaining travel behavior data that more truly reflected underlying behavior. In the first year of the project a prototype of REACT!, a web-based, self administered survey instrument for collecting household travel/activity data was produced. REACT! documents not only the resultant behavior but also the scheduling process that produces that behavior by having each respondent record activities as they are initially planned, updated, and executed. In the second year, following a beta test of REACT! and final program modification, a formal REACT! field study was completed for 47 households who used REACT! to provide 24 hours of travel/activity data over a 7 day period. Ensuing analyses focused on the activity scheduling process. 

Work Completed to Date All proposed tasks have been successfully completed (although continued development and refinement of REACT! continues). The REACT! software was developed, subject to substantial internal and beta testing, followed by a full field survey. Formal analysis of the resulting REACT! data was completed, with results presented at several conferences and papers being submitted to journals. Results include the identification of distinct spatial and temporal behaviors for planned and unplanned activities, with defined gender differences observed. Classification and structural models were developed to identify regularities in scheduling behavior. Follow-on research is focused on integrating REACT! with data from TRACER, a GPS-based vehicle tracking system, and extending the range of REACT! project applications.

This two-year project focused on obtaining travel behavior data that more truly reflects underlying behavior. In the first year of the project a prototype of REACT!, a web-based, self-administered survey instrument for collecting household travel/activity data was produced.REACT! documents not only the resultant behavior but also the scheduling process that produces that behavior by having each respondent record activities as they are initially planned, updated, and executed. In the second year, following a beta test of REACT! and final program modification, a formal REACT! field study was completed for 47 households who used REACT! to provide 24 hours of travel/activity data over a 7 day period. Ensuing analyses focused on the activity scheduling process.

The space-time prisms envisioned by Hagerstrand enclose the locations a person can reach by taking into account various time constraints. This concept has occasionally been used to measure accessibility, but was limited by data availability and computing power. Taking advantages of technological advances, a new procedure utilizing a geographic information system (GIS) is developed to locate facilities within space-time prisms. Data from Portland, Oregon, are applied to demonstrate how the proposed procedure can be used to measure accessibility to health care facilities. The potential of the procedure for measuring accessibility from the activity-based perspective is discussed.

The dynamic process of how individuals organize their activities and travel is often termed activity scheduling. Investigation of the dynamic processes has been the interest of transportation researchers in the past decade, because of its relevance to the effectiveness of congestion management and intelligent transportation systems. To empirically examine this process, a computerized survey instrument was developed to collect household activity scheduling data. The instrument is unique in that it records the evolution of activity schedules from intentions to final outcomes for a weekly period.

This paper summarizes the investigation on the dynamic processes of activity scheduling and trip chaining based on data collected from a pilot study of the instrument. With the data, ordered logit models are applied to identify factors that are related to the scheduling horizon of activities. Results of the empirical analyses show that activities of shorter duration were more likely to be opportunistically inserted in a schedule already anchored by their longer duration counterparts. Additionally, analysis of travel patterns reveals that many trip-chains were formed opportunistically. Travel time required to reach an activity was positively related to the scheduling horizon for the activity , with more distant stops being planned earlier than closer locations.

This two-year project focused on obtaining travel behavior data that more truly reflected underlying behavior. In the first year of the project a prototype of REACT!, a web-based, self-administered survey instrument for collecting household travel/activity data was produced. REACT! documents not only the resultant behavior but also the scheduling process that produces that behavior by having each respondent record activities as they are initially planned, updated, and executed. In the second year, following a beta test of REACT! and final program modification, a formal REACT! field study was completed for 47 households who used REACT! to provide 24 hours of travel/activity data over a 7 day period. Ensuing analyses focused on the activity scheduling process.