The Ethical Challenges and Professional Responses of Travel Demand Forecasters
Thirty years ago scholars first presented convincing evidence that local officials use biased travel demand forecasts to justify decisions based on unstated considerations. Since then, a number of researchers have demonstrated convincingly that such forecasts are systematically optimistic-often wildly so-for reasons that cannot be explained solely by the inherent difficulty of predicting the future. Why do modelers-professional engineers and planners who use quantitative techniques to predict future demand for travel and estimate its potential impact on built and proposed transportation facilities-generate biased forecasts and otherwise tolerate the misuse of their work? On initial consideration, it is tempting to surmise that corrupt modelers are responsible for biased forecasting. Indeed, corruption is the most common explanation of forecasting bias and tales of mercenary behavior are all too common in the field. Data from in-depth interviews with twenty-nine travel demand forecasters throughout the United States and Canada, how-ever, suggest new and different ways to understand the suspect behavior of transportation planning professionals. Those most likely to introduce bias and invite misuse of travel forecasts assume that their technical analyses have little, if any, impact on policy making. For many, this leads to disillusionment and requires responses to cope with feelings of marginalization. Others, untroubled by their apparent lack of influence, are complacent and need ways to avoid the ethical questions of practice. Both types of practitioners circumscribe professional roles and rely on the self-deceptive strategies of evasion and excuse making to mute their own disquieting realities that undermine positive concepts of self. The disillusioned wish not to see that they do not matter and the complacent that they do. Bias and misuse seem to be the unintentional byproducts of these attitudes. Beyond enhancing the understanding of the systemic failures of travel demand modeling, this research suggests practicable steps to reform and outlines an agenda for future work. Attention to these matters is important, not just to avoid expenditures on projects and programs that cannot be justified on the basis of sound utilitarian calculations, but also to restore and preserve the credibility of a profession.
|Date of creation:||01 Sep 2003|
|Contact details of provider:|| Postal: 109 McLaughlin Hall, Mail Code 1720, Berkeley, CA 94720-1720|
Web page: http://www.escholarship.org/repec/its/
More information through EDIRC
References listed on IDEAS
Please report citation or reference errors to , or , if you are the registered author of the cited work, log in to your RePEc Author Service profile, click on "citations" and make appropriate adjustments.:
- Skamris, Mette K. & Flyvbjerg, Bent, 1997. "Inaccuracy of traffic forecasts and cost estimates on large transport projects," Transport Policy, Elsevier, vol. 4(3), pages 141-146, July.
- Brinkman, Anthony & Goldman, Todd, 1998. "Transportation Models In the Policy-Making Process: Uses, Misuses, And Lessons For The Future," Institute of Transportation Studies, Research Reports, Working Papers, Proceedings qt47h925rc, Institute of Transportation Studies, UC Berkeley.
- Mackie, Peter & Preston, John, 1998. "Twenty-one sources of error and bias in transport project appraisal," Transport Policy, Elsevier, vol. 5(1), pages 1-7, January.
- Edwards, Marion & Mackett, Roger L, 1996. "Developing new urban public transport systems : An irrational decision-making process," Transport Policy, Elsevier, vol. 3(4), pages 225-239, October.
- A. Meltzer & Peter Ordeshook & Thomas Romer, 1983. "Introduction," Public Choice, Springer, vol. 41(1), pages 1-5, January.
- Roy T. Meyers, 1996. "If policy analysts are depressed, what should they do about it?," Journal of Policy Analysis and Management, John Wiley & Sons, Ltd., vol. 15(3), pages 438-443.
- Nelson, Robert H, 1987. "The Economics Profession and the Making of Public Policy," Journal of Economic Literature, American Economic Association, vol. 25(1), pages 49-91, March.
- Tore Langmyhr, 2000. "The Rhetorical Side of Transport Planning," European Planning Studies, Taylor & Francis Journals, vol. 8(5), pages 669-684, October.
- Mackett, Roger L. & Edwards, Marion, 1998. "The impact of new urban public transport systems: will the expectations be met?," Transportation Research Part A: Policy and Practice, Elsevier, vol. 32(4), pages 231-245, May.
- Small, K. & Winston, C., 1998. ""The Demand for Transportation: Models and Applications"," Papers 98-99-6, California Irvine - School of Social Sciences.
- Rubin, Thomas A. & Moore II, James E. & Lee, Shin, 1999. "Ten myths about US urban rail systems," Transport Policy, Elsevier, vol. 6(1), pages 57-73, January.
- Goetz, Andrew R. & Szyliowicz, Joseph S., 1997. "Revisiting transportation planning and decision making theory: The case of Denver International Airport," Transportation Research Part A: Policy and Practice, Elsevier, vol. 31(4), pages 263-280, July.
- Kenneth Button & Roger R. Stough (ed.), 1998. "Transport Policy," Books, Edward Elgar Publishing, number 1405.
- A. P. Thirlwall, 1983. "Introduction," Journal of Post Keynesian Economics, M.E. Sharpe, Inc., vol. 5(3), pages 341-344, April.
When requesting a correction, please mention this item's handle: RePEc:cdl:itsrrp:qt9c3330tt. See general information about how to correct material in RePEc.
For technical questions regarding this item, or to correct its authors, title, abstract, bibliographic or download information, contact: (Lisa Schiff)
If references are entirely missing, you can add them using this form.