Transcript Document

Travel Forecasting
for New Starts
The FTA Perspective
September 27, 2004
1
Topics
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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 responsibilities
Accuracy record of forecasts
External scrutiny
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FTA Responsibilities
 Evaluation of “New Starts” proposals
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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
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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
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Exceeded AA forecast:
80-100% of AA forecast:
70-80% of AA forecast:
3 of 19
3 of 19
4 of 19
 1990 assessment
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Exceeded AA forecast:
80-100% of AA forecast:
70-80% of AA forecast:
0 of 10
0 of 10
1 of 10
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Accuracy of Forecasts
 Conclusions
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Forecast accuracy is much better
Risk of large errors still remains
Enhanced quality control is crucial
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External Scrutiny
 Annual
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Office of Management and Budget
Congress
General Accounting Office
 Special studies
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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
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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
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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 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
|
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 Benefits
for Travel Produced in Each Zone
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Detailed Reporting
 Unhappy outcomes
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Previously unknown “properties” of models
Problems with highway time savings
Inconsistencies among models nationally
Problems in definitions of the alternatives
 New opportunities
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Understanding and refinement of projects
Making a better case for projects
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Detailed Reporting
 Brief “make the case” write-up
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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
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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
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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
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User specifications
Filenames
 Table titles
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Calculations in Summit
 User benefit calculations
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Required inputs
Special output file from base alternative
 FTA-standard output file from build alternative
 Zonedistrict equivalence file
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Outputs
Report file – district-to-district user benefits; totals
 Output file – district-to-district user benefits (binary)
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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
TIME OF DAY;
ASSIGNMENT
HBW
Ps/Qs
MODE
CHOICE
TIME OF DAY;
ASSIGNMENT
HBO
Ps/Qs
MODE
CHOICE
NHB
Ps/Qs
TIME OF DAY;
ASSIGNMENT
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Summit Applications to
Compute User Benefits
Summit applications: Alternative versus Base
Alt
HBW
Ps/Qs
Alt
HBO
Ps/Qs
Summit
Base
HBW
Ps/Qs
User
Bens:
D-D &
TEsum
Summit
Base
HBO
Ps/Qs
User
Bens:
D-D &
TEsum
Summit
Alt
NHB
Ps/Qs
Summit
Base
NHB
Ps/Qs
User
Bens:
D-D &
TEsum
District-District
Row/Col-Sums
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Calculations in Summit
 Other features
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Analytical reporting of forecasts
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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
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Research
 Technical methods
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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 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
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Coherent Models
 Consistency with current good practice
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Level playing field
Likelihood of “promises kept”
 Threats to coherency of models
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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?
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Nesting structure and coefficients
Constants and implied effect of unincluded attributes
 Does it reproduce current travel patterns?
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Any beginner can match totals by adjusting Ks
Scrutiny of markets and patterns within the totals
 Does it predict rational responses to change?
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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
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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:
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Transit path selection
Mode choice utility expressions for transit choices
 Consequences of disagreement
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“Better” paths may look worse to mode choice
Build alternatives may lose some trips and benefits
 Consistency crucial; possible exceptions
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Bifurcation of 1st wait time?
Treatment of transfers?
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Network Speeds
 Highway
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Replication of current average travel times
Comparability between alternatives
 Bus
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Relationship to auto speeds
Replication of current average travel times
Handling of “dead” highway links
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Bottom Line
 Purpose of models
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Insights into problems, solutions, benefits
Development of a solid case for a project
 Required performance by models
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Remain consistent with current good practice
Provide coherent insights
Support a coherent story about the project
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