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2010 © CEOs for CITIES 2
KEY FINDINGS
The secret to reducing time Americans spend in peak hour
traffic has more to do with...
2010 © CEOs for CITIES 3
DISTANCE MATTERS
!   In nation’s cities largest, typical traveler spends
200hr/yr in peak period ...
2010 © CEOs for CITIES 4
LONGER TRIP
DISTANCES
AND SPRAWL
SHAPE TRAVEL
TIMES
2010 © CEOs for CITIES 5
A VERY DIFFERENT PICTURE
LONGEST PEAK HOUR TRAVEL
TIMES
Nashville-Davidson TN
Oklahoma City OK
Bi...
2010 © CEOs for CITIES 6
ROADMAP
1.  The Urban Mobility Report
2.  Travel Time Index is flawed concept
3.  UMR overestimat...
2010 © CEOs for CITIES 7
THE URBAN MOBILITY REPORT
!   Produced since 1982 by
Texas Transportation
Institute
!   Provides ...
2010 © CEOs for CITIES 8
UMR CLAIMS
!   Congestion is a big problem
– 46 hrs of delay per person per yr
!   It wastes lots...
2010 © CEOs for CITIES 9
UMR REALITY
!   Impact of distance on travel times ignored
!   UMR rates areas “less congested” e...
2010 © CEOs for CITIES 10
A FLAWED CONCEPT:
THE TRAVEL TIME INDEX (TTI)
!   How much additional time does it take to trave...
2010 © CEOs for CITIES 11
PROBLEMS WITH TTI
!   An unrealistic baseline
– No one expects or can achieve zero
delay/free-fl...
2010 © CEOs for CITIES 12
IS CHICAGO TRAFFIC REALLY
WORSE?
COMPARISON
Average Trip
Un-congested Travel Time
Delay
Total Tr...
2010 © CEOs for CITIES 13
UMR OVERESTIMATES CONGESTION
!   No direct observation of travel time
!   A bad model for estima...
2010 © CEOs for CITIES 14
WEAK BASIS FOR SPEED
ESTIMATES
2010 © CEOs for CITIES 15
CHECKING UMR VALIDITY
!   Do UMR estimates square with other data on variations in
travel over t...
2010 © CEOs for CITIES 16
NATIONAL SURVEY SUGGESTS
TRAVEL TIME, ADJUSTED FOR
DISTANCE, ACTUALLY DECLINED
2010 © CEOs for CITIES 17
UMR NOT CONSISTENT WITH INRIX
The average UMR estimate in 70% higher than the average INRIX obse...
2010 © CEOs for CITIES 18
FUEL CONSUMPTION ESTIMATES
BASED ON OUTDATED STUDY
!   RAUS study done in 1981
!   Data: 1973-76...
2010 © CEOs for CITIES 19
UMR v. DOE FUEL ECONOMY
CURVES
2010 © CEOs for CITIES 20
TOWARD BETTER MEASURES OF
URBAN TRANSPORTATION SYSTEMS
TWO KEY TASKS
!   Correcting the UMR
!   ...
2010 © CEOs for CITIES 21
CORRECTING THE UMR ESTIMATE
!   Recompute UMR, assuming
– Realistic baseline
– Better travel tim...
2010 © CEOs for CITIES 22
A NEW FOCUS
!   Shift to accessibility measures
!   Start with shorter distances actually travel...
2010 © CEOs for CITIES 23
THE ROLE OF
LONGER TRIP
DISTANCES
2010 © CEOs for CITIES 24
THE PAYOFF
!   If every one of the top 50 metro areas achieved
same level of peak hr travel dist...
2010 © CEOs for CITIES 25
SOME CITIES HAVE MADE
PROGRESS
THE UMR VIEW: Congestion got worse
Travel Time Index
1982
1.07
20...
2010 © CEOs for CITIES 26
BUILDING A BETTER MEASURE
!   Emphasize access to destinations
!   Add measures of land use & tr...
2010 © CEOs for CITIES 27
CONCLUSIONS
!   The Travel Time Index (TTI) is a misleading guide to
assessing transportation sy...
The Connectivity Declaration - Joe Cortright, President of Impresa
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The Connectivity Declaration - Joe Cortright, President of Impresa

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The Connectivity Declaration - Joe Cortright, President of Impresa

  1. 1. 2010 © CEOs for CITIES 2 KEY FINDINGS The secret to reducing time Americans spend in peak hour traffic has more to do with how we build our cities than how we build our roads.
  2. 2. 2010 © CEOs for CITIES 3 DISTANCE MATTERS !   In nation’s cities largest, typical traveler spends 200hr/yr in peak period travel !   But in best performing cities, travelers spend 40 fewer hrs in peak traffic !   Why? They travel shorter distances
  3. 3. 2010 © CEOs for CITIES 4 LONGER TRIP DISTANCES AND SPRAWL SHAPE TRAVEL TIMES
  4. 4. 2010 © CEOs for CITIES 5 A VERY DIFFERENT PICTURE LONGEST PEAK HOUR TRAVEL TIMES Nashville-Davidson TN Oklahoma City OK Birmingham AL Richmond VA HOURS 284 252 245 242 RANK 1 2 3 4 UMR RATE 31 38 34 44 SHORTEST PEAK HOUR TRAVEL TIMES New York-Newark NY-NJ-CT Sacramento CA Chicago IL-IN HOURS 122 136 163 RANK 46 48 51 UMR RATE 14 23 21
  5. 5. 2010 © CEOs for CITIES 6 ROADMAP 1.  The Urban Mobility Report 2.  Travel Time Index is flawed concept 3.  UMR overestimates congestion 4.  Fuel economy estimates contain errors 5.  Developing better measures
  6. 6. 2010 © CEOs for CITIES 7 THE URBAN MOBILITY REPORT !   Produced since 1982 by Texas Transportation Institute !   Provides estimates and rankings of congestion
  7. 7. 2010 © CEOs for CITIES 8 UMR CLAIMS !   Congestion is a big problem – 46 hrs of delay per person per yr !   It wastes lots of energy !   It’s getting worse !   It costs us a lot of money – $750 per person up from $290 in 1982
  8. 8. 2010 © CEOs for CITIES 9 UMR REALITY !   Impact of distance on travel times ignored !   UMR rates areas “less congested” even if residents have to travel farther and longer !   Congestion estimated from unattainable ideal !   Speeds estimated from inaccurate model, mechanically converting higher volumes into slower speeds !   Other evidence shows commute times have not increased !   Fuel economy incorrectly estimated, overstating costs
  9. 9. 2010 © CEOs for CITIES 10 A FLAWED CONCEPT: THE TRAVEL TIME INDEX (TTI) !   How much additional time does it take to travel a given distance at peak vs off-peak !   Example: – Trip takes 20 min off-peak (free flow) – Trip takes 25 min at peak – TTI = 25/20 = 1.25 – 5 min of delay
  10. 10. 2010 © CEOs for CITIES 11 PROBLEMS WITH TTI !   An unrealistic baseline – No one expects or can achieve zero delay/free-flow in the peak hr !   TTI ignores variations in travel distances among metro areas
  11. 11. 2010 © CEOs for CITIES 12 IS CHICAGO TRAFFIC REALLY WORSE? COMPARISON Average Trip Un-congested Travel Time Delay Total Travel Time TRAVEL TIME INDEX CHARLOTTE 19mi 38.4min 9.6mi 48.0mi 1.25 CHICAGO 13.5mi 22.8mi 9.8min 32.6mi 1.43
  12. 12. 2010 © CEOs for CITIES 13 UMR OVERESTIMATES CONGESTION !   No direct observation of travel time !   A bad model for estimating travel time !   UMR results don’t square with other measures
  13. 13. 2010 © CEOs for CITIES 14 WEAK BASIS FOR SPEED ESTIMATES
  14. 14. 2010 © CEOs for CITIES 15 CHECKING UMR VALIDITY !   Do UMR estimates square with other data on variations in travel over time and space? – Inrix: Real time speed data – NHTS: Comprehensive travel survey data – Census/ACS: Reported journey-to-work travel time data
  15. 15. 2010 © CEOs for CITIES 16 NATIONAL SURVEY SUGGESTS TRAVEL TIME, ADJUSTED FOR DISTANCE, ACTUALLY DECLINED
  16. 16. 2010 © CEOs for CITIES 17 UMR NOT CONSISTENT WITH INRIX The average UMR estimate in 70% higher than the average INRIX observation: UMR = 1.24 INRIX = 1.14
  17. 17. 2010 © CEOs for CITIES 18 FUEL CONSUMPTION ESTIMATES BASED ON OUTDATED STUDY !   RAUS study done in 1981 !   Data: 1973-76 GM cars av 13.6mpg !   Fuel economy estimates “The above relationship is good only for speeds up to about 35mph”
  18. 18. 2010 © CEOs for CITIES 19 UMR v. DOE FUEL ECONOMY CURVES
  19. 19. 2010 © CEOs for CITIES 20 TOWARD BETTER MEASURES OF URBAN TRANSPORTATION SYSTEMS TWO KEY TASKS !   Correcting the UMR !   Developing new measures that emphasize accessibility
  20. 20. 2010 © CEOs for CITIES 21 CORRECTING THE UMR ESTIMATE !   Recompute UMR, assuming – Realistic baseline – Better travel time data (Inrix) – Lower travel time costs – Drop fuel model !   Reduces UMR cost estimate 70% !   UMR overstates by $49 billion
  21. 21. 2010 © CEOs for CITIES 22 A NEW FOCUS !   Shift to accessibility measures !   Start with shorter distances actually traveled in many metro areas !   Use a realistic baseline – What is actually attained in best of class metro areas – Look at 90th percentile performers !   Quantify time, energy, and economic costs of sprawl- lengthened commute travel
  22. 22. 2010 © CEOs for CITIES 23 THE ROLE OF LONGER TRIP DISTANCES
  23. 23. 2010 © CEOs for CITIES 24 THE PAYOFF !   If every one of the top 50 metro areas achieved same level of peak hr travel distances as best performing cities, their residents would drive about 40B fewer mi/yr and use 2B fewer gal of fuel, at savings of $31B annually.
  24. 24. 2010 © CEOs for CITIES 25 SOME CITIES HAVE MADE PROGRESS THE UMR VIEW: Congestion got worse Travel Time Index 1982 1.07 2007 1.29 THE REALITY: Trips and travel time got shorter Average Trip Travel Time 1982 19.6mi 53min 2007 16.0mi 43min
  25. 25. 2010 © CEOs for CITIES 26 BUILDING A BETTER MEASURE !   Emphasize access to destinations !   Add measures of land use & trip distance !   Incorporate better data !   Adopt open, multidisciplinary process !   Aim to guide policy and assess investments
  26. 26. 2010 © CEOs for CITIES 27 CONCLUSIONS !   The Travel Time Index (TTI) is a misleading guide to assessing transportation system performance and costs and inherently rewards sprawl and penalizes compact development !   The UMR methodology is flawed, and its results can’t be reconciled to real world observations !   Sprawl, not congestion, is the bigger source of time loss, energy waste and excess costs in most metro areas !   New measures that emphasize accessibility should guide our transportation policy

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