Ming S. Lee

On the structure of weekly activity/travel patterns

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 ones 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.

EXPERIMENTS WITH COMPUTERIZED SELF-ADMINISTRATIVE ACTIVITY SURVEY

The process of activity scheduling is crucial to the understanding of travel behavior changes. In-depth research is urgently needed to unearth this process. A new computer program, REACT!, was 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 geographic information system 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’s performance. Preliminary analysis validated the program’s capability of guiding participants to complete data entry tasks on their own; thus, the objective of reducing the cost of human resources for such a computerized survey is achieved. Other positive results were obtained regarding the objectives of reducing instrumental biases and expanding program capabilities. Areas for improvement were identified in the pilot study. On the basis of the findings, REACT! represents an ideal platform for a computerized household survey that can produce data for activity-based travel models.