Abstract
Advanced traveler information systems (ATISs) offer benefits to travelers and may improve transportation system performance in congested areas. An understanding of how information affects travelers' decisions can help in evaluating benefits and designing demand management strategies. The objective of the present study was to explore how people deal with unexpected congestion during the pretrip stage and how they might respond to ATISs. Travelers' routes, departure times, and mode selection decisions were investigated through a survey of Bay Area automobile commuters. The effects of various factors such as sources of congestion information (radio traffic reports versus observation), trip characteristics, and route attributes on travelers' responses to unexpected congestion were examined. The pretrip response to future ATIS technologies was explored through stated preferences (hypothetical scenarios). A combined reported preference and stated preference model of traveler response was developed by using the multinomial logit formulation. The estimations indicate that travel time and information are important determinants of changes in travel decisions in response to unexpected delays. The model indicates a strong relationship between reported and stated preferences. The results indicate that ATISs overcome behavioral inertia and that individuals are more likely to change their travel patterns in response to prescriptive information. More specific findings and their implications for ATIS design are also discussed.
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