Metropolitan Travel Forecasting TRB Special Report 288

1. Metropolitan Travel ForecastingTRB Special Report 288 Mn/DOT Statewide Travel Demand Modeling Committee August 29, 2007 August 29, 2007

2. Background • Environmental Defense Fund vs. Metropolitan Washington Council of Governments • National Research Council peer review convenes to determine is MWCOG travel demand modeling process “state of the practice” • FHWA, FTA, OST funded TRB Special Report 288 – “Metropolitan Travel Forecasting” August 29, 2007

3. “Although travel demand models have been used in transportation planning for some four decades, there are few universally accepted guidelines or standards of practice for these models or their application” (TRB 2003). August 29, 2007

4. TRB Special Report 288 - Objectives • Describe current state of the practice • Evaluate current state of the practice, including deficiencies • Recommend improvements http://onlinepubs.trb.org/onlinepubs/sr/sr288.pdf August 29, 2007

5. TRB Special Report 288 - Process • Established high level committee • Conducted a web based survey of all MPOs • Reviewed literature • Interviewed 16 states and MPOs • Invited presentations from federal agencies August 29, 2007

6. GeneralObservations • Despite changes in travel demand modeling responsibilities & expectations the basic practice has changed little in recent years • Most urban travel demand models are not based on a coherent theory of travel behavior – Meyer and Miller, 2001 • Travel demand models are deterministic in an environment that is increasingly more complex and probabilistic • There are no commonly agreed upon standards for an acceptable range of error August 29, 2007

7. GeneralObservations - Continued • Gravity models may be insensitive to policy, socioeconomic or geographic variables that influence travel behavior • Resource constraints hamper many seeking to improve data inputs and strengthen modeling practices • There are a number of MPOs and State DOTs implementing improved practices for model estimation, model calibration, and model validation August 29, 2007

8. TRB 288 - Findings • The basic modeling approach remains a sequential 4-step process • Some are experimenting with tour-based models and land use + travel models • There is no single approach that is “correct” for all applications or all MPOs. • Travel forecasting tools should be appropriate for the questions being posed and the analysis being conducted. August 29, 2007

9. Snapshot of Survey Results • 16 states provide MPOs with guidance aimed at standardizing modeling practice • 14 states perform model development and forecasting for many or all MPOs in their state • 89% of MPOs with population exceeding one million do their own model development • 16 states have statewide MPO model user groups • 70% of large & medium MPOs identified modeling features that need improvement • About 20% of small & medium sized MPOs & almost 40% of large MPOs are considering replacing existing models with activity or tour based models August 29, 2007

10. Shortcomings • Demands on forecasting models have grown. Existing models are inadequate to address many newer policy concerns, including: • Estimating motor vehicle emissions based on speeds and time of day • Estimating new travel generated by new capacity – induced travel • Evaluating alternative land use policies • Estimating freight movements & non-motorized trips • Modeling yields less satisfactory results as problems being studied become more disaggregate & more linked to individual travel behavior August 29, 2007

11. Shortcomings (2) • Current models have inherent weaknesses in: • Associating traveler characteristics with trips • Dealing with time of day variations & peak spreading • Estimating traveler responses to: • Congestion • Public policy changes such as road pricing, land use controls, transit vouchers • Emergencies • Considering travel impacts from demographic changes & estimating transportation affects on economic development August 29, 2007

12. Shortcomings (3) • Poor technical practice • Inadequate data • Failure to deal with uncertainty in model estimates • Inability to represent dynamic conditions • Reliability of land use and demographic forecasts • Failure to maintain consistency among all elements of a forecast, especially around growth & land use projections • Lack of validation processes & procedures August 29, 2007

13. Improvements to the 4-Step Process • Improved measure of arterial congestion(modeled delay at arterial intersections) • Inclusion of both highway + transit in trip distribution • Improved trip distribution models (destination choice) • Improved modeling of non-motorized trips • Improved sensitivity (validation) testing August 29, 2007

14. Advanced Models Three metropolitan areas/regions have implemented advanced models; 8 more are in design • Reflect decision patterns/interactions of households • More completely represent supply-side network to account for details of congestion throughout the day August 29, 2007

15. Advanced models - continued • Improved land use models • Tour based models that recognize that trips have multiple purposes and stops • Activity based models that recognize complex interactions between activity & travel behavior & are capable of producing regional scale microsimulation • Discrete-choice modeling - travel made by individuals not TAZs • Supply-side models • TRANSIMS August 29, 2007

16. FTA Model • New Starts program requires before and after studies • Applicants must certify the adequacy of technical methods, including best available data and quality assurance reviews • Must use the SUMMIT FTA reporting tool to calculate user benefits and assess quality control • FTA & FHWA conduct certifications of every TMA at least every 4 years to ensure adequacy of the planning process August 29, 2007

17. Obstacles • Can advanced models be implemented for reasonable costs and provide significant improvements? • Federal involvement & funding for models has decreased and is severely deficient – yet federal planning and environmental requirements have increased August 29, 2007

18. Barriers to Change • Resource limitations • Uncertainty about whether new models will be better than the ones they replace • Lack of coordination among stakeholders • Inadequate investment in development & transfer of new techniques August 29, 2007

19. Additional Barriers • “…virtually all MPOs believe it is either difficult or very difficult to hire experienced travel modelers”. (UTM 2006) • Unavailability of vendor supplied software to address shortcomings & needs August 29, 2007

20. MPORecommendations • Create a national metropolitan cooperative research program • Pool resources for modeling enhancements • Cooperate in research and development studies • MPOs should conduct formal peer reviews of their modeling practices August 29, 2007

21. MPORecommendations (Continued) • Individual MPOs & universities could form partnerships to foster research & implementation of advanced practices • MPOs and other planning organizations should conduct reasonableness checks of demand and costs forecasts for major projects • MPOs with advanced modeling practices should document and share experiences August 29, 2007

22. State Transportation Agency Recommendations • Support development of a national MPO cooperative research program • Provide support for model user groups • Work in cooperation with MPOs to evaluate socioeconomic forecasts • Coordinate with MPOs on statewide and metropolitan models & data needs August 29, 2007

23. Federal Government Recommendations • Support & provide funding for incremental improvements to 4-step and trip-based models • Support & provide funding for advanced approaches, including activity based modeling • Continue TMIP • Increase funding to support modeling • Continue the MPO certification process with checklists to clarify minimum expectations • Allow MPOs substantial flexibility in their travel demand practices August 29, 2007

24. Opportunities for Intergovernmental Cooperation • Establish appropriate goals, responsibilities, and means of improving travel forecasting practices • Compare the performance of conventional vs. traditional models • Collaborate on data collection • Updating travel surveys • Collecting freight flows • Expanding traffic counts • Measuring traffic speeds August 29, 2007

25. Questions for Minnesota Modelers • How well is the traditional 4-step process meeting your needs? • Do you agree with the limitations outlined in TRB 288? • From your perspective, how serious are the limitations cited in the report? • To what extent do these limitations negatively influence your ability to effectively forecast future conditions and/or address policy, program, or project questions and decisions in your area? • Of the limitations cited in the report, which are most problematic? Which currently have little or no impact on forecasting results of your plans, policies, or programs? August 29, 2007

26. What is your reaction to the recommendations included in the report? • Which of the recommendations would be most helpful in strengthening metropolitan forecasting? • Do you have additional ideas or suggestions for improving existing data, models, processes or procedures? • What actions, strategies or process changes have you implemented to enhance metropolitan forecasting? August 29, 2007

27. Thank you! Please forward comments, ideas and suggestions to: Jonette Kreideweis 651-366-3854 jonette.kreideweis@dot.state.mn.us August 29, 2007