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Travel Forecasting for New Starts
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  1. Travel Forecasting for New Starts The FTA Perspective September 27, 2004

  2. Topics • Why FTA cares about forecasts • What FTA is doing about forecasts • What FTA requires about forecasting • What project sponsors should be doing

  3. Why FTA cares about forecasts FTA responsibilities Accuracy record of forecasts External scrutiny

  4. FTA Responsibilities • Evaluation of “New Starts” proposals • FTA Major Capital Investment Program • Discretionary funding • Annual recommendations to Congress based on mandated criteria: * Strong ties to travel forecasting

  5. FTA Responsibilities • Count all of the benefits (and costs) • Maintain a level playing field • Ensure that promises can be kept • Make solid cases for good projects

  6. Accuracy of Forecasts • FTA analysis of 19 latest New Starts • Full Funding Grant Agreement • Subsequent to 1990 Pickrell report • Open to service • Documented guideway ridership forecasts

  7. Accuracy of Forecasts • 2003 assessment • Exceeded AA forecast: 3 of 19 • 80-100% of AA forecast: 3 of 19 • 70-80% of AA forecast: 4 of 19 • 1990 assessment • Exceeded AA forecast: 0 of 10 • 80-100% of AA forecast: 0 of 10 • 70-80% of AA forecast: 1 of 10

  8. Accuracy of Forecasts • Conclusions • Forecast accuracy is much better • Risk of large errors still remains • Enhanced quality control is crucial

  9. External Scrutiny • Annual • Office of Management and Budget • Congress • General Accounting Office • Special studies • Office of the Inspector General • General Accounting Office

  10. What FTA is Doing about Forecasts User benefits Detailed reporting of forecasts Summit Research

  11. User Benefits Transportation system user benefits User benefits are the changes in mobility for individual travelers that are caused by a project or policy change, measured as hours of travel time savings, and summed over all travelers.

  12. User Benefits • Changes in mobility • Shorter transit times: in-vehicle, walk, wait • Fewer transfers • Changes in unmeasured characteristics • Relief of crush loading conditions • (Shorter auto times due to lower congestion) • Project-oriented growth [new option in 2003]

  13. Detailed Reporting • Reporting of trips and user benefits • Totals across all socio-economic segments • District-to-district summaries  reports • Row totals, column totals  thematic maps • Frequency distributions of per-trip benefits • Results for individual socio-economic segments

  14. Reporting: Transportation Benefitsfor Individual Travel Markets Report 1-5 Total User Benefits (hours) for the Build Alternative All Transit-Access Markets Home-Based-Work Production Attraction District District | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 | Total -------------+--------------------------------------------------------------------------------------+------ 1 CBD | 4 -1 4 0 5 0 0 6 15 1 0 9 0 0 0 0 0 | 41 2 Urban | 194 86 67 0 39 0 0 73 281 8 0 220 0 15 0 0 0 | 984 3 N Suburb | 135 50 37 0 21 0 0 10 39 2 0 54 0 3 0 0 0 | 351 4 N Rural | 1 1 3 0 1 0 0 0 2 0 0 2 0 0 0 0 0 | 10 5 W Suburb | 219 140 41 0 93 0 0 23 240 4 0 83 0 3 0 0 0 | 846 6 NW Suburb | -13 2 7 0 0 0 0 1 10 0 0 8 0 0 0 0 0 | 15 7 NW Rural | 42 18 13 0 5 0 0 2 4 0 0 8 0 0 0 0 0 | 93 8 S Suburb | 150 86 14 0 17 0 0 130 63 7 0 72 0 1 0 0 0 | 540 9 SW Suburb | 201 147 17 0 108 0 0 31 195 5 0 62 0 1 0 0 0 | 766 10 SE Suburb | 18 12 3 0 4 0 0 3 7 0 0 14 0 0 0 0 0 | 62 11 SE Rural | 2 4 2 0 1 0 0 1 3 1 0 8 0 0 0 0 0 | 22 12 E Suburb | 832 467 88 0 111 0 0 97 191 25 0 909 0 20 0 0 0 | 2739 13 E Rural | 0 3 3 0 1 0 0 1 3 0 0 9 0 0 0 0 0 | 20 14 NE Suburb | 104 49 13 0 10 0 0 5 11 2 0 78 0 3 0 0 0 | 276 15 NE Rural | -41 -16 -2 0 -3 0 0 -1 -1 0 0 -7 0 0 0 0 0 | -72 16 External | 835 345 123 0 79 0 0 37 95 7 0 138 0 8 0 0 0 | 1668 17 Other | 2 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 | 4 -------------+--------------------------------------------------------------------------------------+------ Total | 2684 432 493 0 1158 0 0 0 0 | | 1396 0 0 420 61 1665 55 0 | 8364

  15. Reporting: Transportation Benefitsfor Travel Produced in Each Zone

  16. Detailed Reporting • Unhappy outcomes • Previously unknown “properties” of models • Problems with highway time savings • Inconsistencies among models nationally • Problems in definitions of the alternatives • New opportunities • Understanding and refinement of projects • Making a better case for projects

  17. Detailed Reporting • Brief “make the case” write-up • The case for your project as you and FTA can make it given the “justification” criteria in TEA-21 • “Three” pages supported by your forecasts • Problem(s) that you are trying to address • Causes of the problem(s) • Specific ways the project addresses the problem(s) • Reasons that the project is preferable to lower-cost options

  18. Calculations in Summit • User benefit calculations • Embedded function • Several (in-stream) runs per build alternative • For each mode choice run (purpose; time of day?) • For summations across purposes, times of day • User specifications • Filenames • Table titles

  19. Calculations in Summit • User benefit calculations • Required inputs • Special output file from base alternative • FTA-standard output file from build alternative • Zonedistrict equivalence file • Outputs • Report file – district-to-district user benefits; totals • Output file – district-to-district user benefits (binary)

  20. Special Mode Choice Output Files for Summit User Benefits Prices/Quantities files from mode choice application HBW HBO NHB TRIP GEN; TRIP DIST TRIP GEN; TRIP DIST TRIP GEN; TRIP DIST MODE CHOICE HBW Ps/Qs MODE CHOICE HBO Ps/Qs MODE CHOICE NHB Ps/Qs TIME OF DAY; ASSIGNMENT TIME OF DAY; ASSIGNMENT TIME OF DAY; ASSIGNMENT

  21. Summit Applications to Compute User Benefits Summit applications: Alternative versus Base Alt HBW Ps/Qs Alt HBO Ps/Qs Alt NHB Ps/Qs Summit Summit Summit Base HBW Ps/Qs Base HBO Ps/Qs Base NHB Ps/Qs User Bens: D-D & TEsum User Bens: D-D & TEsum User Bens: D-D & TEsum Summit District-District Row/Col-Sums

  22. Calculations in Summit • Other features • Analytical reporting of forecasts • Row-sums and column sums  GIS • Selected rows and columns  GIS • Trip-length frequency distributions  grapher • Trip tables stratified by + and – user benefits • Analytical summaries of trip tables • Software interfaces: TP+ TransCAD Emme/2 MinUTP TRANPLAN

  23. Research • Technical methods • Reliable quantification of congestion relief • Reasonable alternative-specific constants • Synthesis of data on guideway ridership • Approaches to quality control • Others • Guidance and requirements

  24. What FTA Requiresabout Forecasting for New Starts • Models that tell a coherent story • Forecasts that can be explained • A case for the project built upon insights obtained from the forecasts

  25. Coherent Models • Consistency with current good practice • Level playing field • Likelihood of “promises kept” • Threats to coherency of models • Naïve or less-than-rigorous calibration and validation • Incorrect travel markets represented in person-trip tables • Odd properties in mode choice models • Inconsistencies between transit path-builder and mode choice • Inaccurate network speeds for auto and bus travel

  26. Model Calibration, Validation • Does it tell a coherent story about behavior? • Nesting structure and coefficients • Constants and implied effect of unincluded attributes • Does it reproduce current travel patterns? • Any beginner can match totals by adjusting Ks • Scrutiny of markets and patterns within the totals • Does it predict rational responses to change? • For changes inherent in New Starts projects • For all model components

  27. Travel Markets • Trip productions & traveler characteristics • Production-attraction flows • Characteristics of travelers • Implications for mode choice • Calibration • Forecasting

  28. Mode Choice • Unusual coefficients • Bizarre alternative-specific constants • Non-Logit decision rules • Problems in choice-set formation

  29. Transit Path-Builder and Mode Choice Model • Conformance between parameters in: • Transit path selection • Mode choice utility expressions for transit choices • Consequences of disagreement • “Better” paths may look worse to mode choice • Build alternatives may lose some trips and benefits • Consistency crucial; possible exceptions • Bifurcation of 1st wait time? • Treatment of transfers?

  30. Network Speeds • Highway • Replication of current average travel times • Comparability between alternatives • Bus • Relationship to auto speeds • Replication of current average travel times • Handling of “dead” highway links

  31. Bottom Line • Purpose of models • Insights into problems, solutions, benefits • Development of a solid case for a project • Required performance by models • Remain consistent with current good practice • Provide coherent insights • Support a coherent story about the project