Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
I hope you will find the conference to be informative. I encourage you to actively participate in discussions dur- ing the breakout sessions. CONFERENCE PARTICIPANTS AND AGENDA Ken Cervenka I would like to welcome you to this conference and to Austin. As of yesterday afternoon, 200 people were reg- istered for the conference. Participants come from met- ropolitan planning organizations (MPOs), state departments of transportation, transit agencies, federal agencies, universities, consultants, software developers, and other groups. The conference began yesterday with two well- attended workshops. After the opening session this morning, the afternoon includes breakout sessions addressing key issues. Many of you completed an online survey to help identify topics of interest for discussion during the breakout sessions. The session moderators have a copy of the survey results and will be using them to help guide discussion after the presentations. The clos- ing session tomorrow afternoon will summarize some of the key themes emerging from the sessions, as well as identify future research, technology transfer, and train- ing needs to advance the state of the practice. I hope you find the conference to be educational and stimulating. I encourage you to actively participate in the breakout sessions and to share your ideas and experi- ences with others. TRAVEL DEMAND MODELING AND PUBLIC POLICY Frank Koppelman As Chandra Bhat noted, the past 10 years have seen major advancements in activity- based demand modeling and land use modeling. The 1970s and 1980s were also an important time for fundamental research in these areas. We have seen progress during this period in both advancing the state of the art and in narrowing the gap between the state of the practice and the state of the art in travel demand modeling. My comments focus on the link between the modeling community and practitioners and decision makers. There are two issues that tend to separate modelers and practi- tioners and slow the process of advancing transportation practice: limited communication and differences in val- ues between the two groups. To improve communication, decision makers must provide a clear statement of forecast needs to modelers. Modelers then need to present their work in a way that focuses on issues relevant to decision makers and in a way that helps a nontechnical audience understand very technical results. Modelers and policy makers have two unique sets of values. Modelers tend to place high priority on the tech- nical properties of models and their ability to represent accurately the behavior of individuals with respect to activity participation and travel. Modelers recognize that transportation is, of course, only one aspect of broad public policy; nonetheless, their emphasis is on the preci- sion of the transportation and, sometimes, related mod- els. Conversely, public decision makers face a range of issues, including schools, law enforcement, emergency services, water and sewer services, economic develop- ment, and other community needs as well as transporta- tion services. Their focus is inherently broader in scope and less concerned with the causal and econometric ele- ments of predictive models. They do not necessarily see an advantage in the evolutionary change from historical models, which were driven by statistical descriptions and simple relationships, to current models, which focus pri- marily on understanding and representing causality. Causality is very complex and is not one- dimensional. Understanding causality is not only a difficult aspect of modeling; it is difficult to explain to policy makers. Different perspectives on the view of models in the decision process are illustrated in Figures 1 and 2, attrib- utable to my colleague, Joseph Schofer. Figure 1 illus- trates the modeling process from the perspective of a decision maker. As shown in the figure, policy makers tend to view the model as a relatively modest part of the decision- making process. Policy makers typically view other factors as more important than the model results and focus on information that addresses these factors. As illustrated in Figure 2, modelers focus almost exclusively on the model and its properties. Other fac- tors are considered to be minor. There is obviously a need to bring these groups closer together in developing a common understanding of the decision- making process and how model results can assist policy makers. 2 INNOVATIONS IN TRAVEL DEMAND MODELING, VOLUME 1 Decision Maker Information: âWhat-if?â Modeler The Model Other Factors FIGURE 1 Decision makersâ view of modeling.
