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Travel Forecasting for New Starts

The FTA Perspective

September 27, 2004

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Topics

Why FTA cares about forecasts What FTA is doing about forecasts What FTA requires about forecasting What project sponsors should be doing

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Why FTA cares about forecasts

FTA responsibilitiesAccuracy record of forecastsExternal scrutiny

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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

*

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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

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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

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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

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Accuracy of Forecasts

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

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External Scrutiny

Annual Office of Management and Budget Congress General Accounting Office

Special studies Office of the Inspector General General Accounting Office

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What FTA is Doing about Forecasts

User benefits Detailed reporting of forecasts Summit Research

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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.

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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]

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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

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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

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Reporting: Transportation Benefitsfor Travel Produced in Each Zone

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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

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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

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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 specificationsFilenamesTable titles

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Calculations in Summit

User benefit calculations Required inputs

Special output file from base alternativeFTA-standard output file from build alternativeZonedistrict equivalence file

OutputsReport file – district-to-district user benefits; totalsOutput file – district-to-district user benefits (binary)

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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

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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

SummitBase

HBO Ps/Qs

User Bens: D-D & TEsum

Alt NHB Ps/Qs

SummitBase

NHB Ps/Qs

User Bens: D-D & TEsum

Summit District-District

Row/Col-Sums

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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+ TransCADEmme/2 MinUTPTRANPLAN

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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

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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

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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

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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

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Travel Markets

Trip productions & traveler characteristics Production-attraction flows Characteristics of travelers Implications for mode choice

Calibration Forecasting

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Mode Choice

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

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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?

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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

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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