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Travel Forecasting for New Starts

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What FTA is doing about forecasts. What FTA requires ... Alt HBO Ps/Qs. Summit. Base HBO Ps/Qs. User Bens: D-D & TEsum. Alt NHB Ps/Qs. Summit. Base NHB Ps/Qs ... – PowerPoint PPT presentation

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Title: Travel Forecasting for New Starts


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
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