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

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Presentation on theme: "1 Travel Forecasting for New Starts The FTA Perspective September 27, 2004."— Presentation transcript:

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

2 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 3 Why FTA cares about forecasts  FTA responsibilities  Accuracy record of forecasts  External scrutiny

4 4 FTA Responsibilities  Evaluation of “New Starts” proposals FTA Major Capital Investment Program Discretionary funding Annual recommendations to Congress based on mandated criteria: Mobility *Environment * Land use *Operating efficiency * Cost-effectiveness *Finance * Strong ties to travel forecasting *

5 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 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 7 Accuracy of Forecasts  2003 assessment Exceeded AA forecast:3 of % of AA forecast:3 of % of AA forecast:4 of 19  1990 assessment Exceeded AA forecast:0 of % of AA forecast:0 of % of AA forecast:1 of 10

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

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

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

11 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 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 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 14 Reporting: Transportation Benefits for 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 | | Total CBD | | 41 2 Urban | | N Suburb | | N Rural | | 10 5 W Suburb | | NW Suburb | | 15 7 NW Rural | | 93 8 S Suburb | | SW Suburb | | SE Suburb | | SE Rural | | E Suburb | | E Rural | | NE Suburb | | NE Rural | | External | | Other | | Total | | | | 8364

15 15 Reporting: Transportation Benefits for Travel Produced in Each Zone

16 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 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 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 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 20 Special Mode Choice Output Files for Summit User Benefits TRIP GEN; TRIP DIST MODE CHOICE HBW Ps/Qs HBW TIME OF DAY; ASSIGNMENT TRIP GEN; TRIP DIST MODE CHOICE HBO Ps/Qs HBO TIME OF DAY; ASSIGNMENT TRIP GEN; TRIP DIST MODE CHOICE NHB Ps/Qs NHB TIME OF DAY; ASSIGNMENT Prices/Quantities files from mode choice application

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

22 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/2MinUTP TRANPLAN

23 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 24 What FTA Requires about 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 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 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 27 Travel Markets  Trip productions & traveler characteristics  Production-attraction flows  Characteristics of travelers  Implications for mode choice Calibration Forecasting

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

29 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 1 st wait time? Treatment of transfers?

30 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 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


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