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Road Capacity and Allocation of Time

Road Capacity and Allocation of Time. David M Levinson University of Minnesota Seshasai Kanchi ICF Consulting 81 st Transportation Research Board Meeting 16 th January 2002. Levinson, David and Seshasai Kanchi (2002) Road Capacity and Allocation of Time,

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Road Capacity and Allocation of Time

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  1. Road Capacity and Allocation of Time David M Levinson University of Minnesota Seshasai Kanchi ICF Consulting 81st Transportation Research Board Meeting 16th January 2002 Levinson, David and Seshasai Kanchi (2002) Road Capacity and Allocation of Time, Journal of Transportation and Statistics 5(1) pp 25-46. http://nexus.umn.edu/Papers/RoadCapacity.pdf

  2. Outline • Introduction • Data • Travel Time and Activity Duration Analysis • Theory of Daily Time Budgets • Methodology • Results • Conclusions

  3. Introduction • Travel and Activity are Two Sides of the Same Coin • Time in Travel = f (Time at Activity, # Trips) • Primary Activities Considered: Home, Work, Shop and Other • Daily Activity Budget (24 hrs)

  4. Data • 1990/91 and 1995/96 Nationwide Personal Transportation Survey • 1990 and 1995 Federal Highway Administration Highway Statistics • Individuals whose total activities did not add to 1440 minutes (24 hrs), excluded • This study looks only at adults, 18-65 years of age • Excluded travelers with a daily shopping time greater than 420 minutes

  5. Activity Duration Calculation

  6. * Denotes Significance at 95% level Travel time and Activity duration Comparison of 1990 and 1995 NPTS

  7. Comparison of Travel and Activity Patterns of 1990 and 1995 NPTS • Time Spent at Home Decreased for Non Workers and Female Workers • Time at Home in 1990 Substituted for Work in 1995, especially for Female Workers • Time Spent at Other Declined for Workers but Increased for Non-Workers • Overall Travel Times have either remained Stable or Increased, but not significant

  8. S1: Supply before S2: Supply after Price of Travel P1 P2 Demand Q2 Q1 Quantity of Travel (VMT) Induced Travel

  9. How does Highway Expansion affect Travel and Activity Patterns • Makes network becomes faster, higher attainable speeds lead to time savings in travel • Increases accessibility • Broadens commuter’s travel choices • More non-travel activities • Individuals maximize their utility

  10. Travel Time (T) S1 S2 Fixed Daily Time Budget “Demand” Line +ve 1440 minutes U Time Spent Traveling Decreases TS1 Utility Increases with Expansion TS2 Activity Duration (A) AS1 AS2 1440 minutes Time Spent at Activities Decreases Travel and Activity Duration Production Function

  11. Model Estimation • Seemingly Unrelated Regression Estimation (SURE) is used • They use asymptotically efficient, feasible generalized least squares estimation • It overrules the assumption of OLS that error residuals are not interrelated

  12. Description of Variables T90i Time spent at activity "i" in 1990 i Index of activities (travel to and duration at home, work, shop and other) A Age D Local population Density G Gender H Household Income levels LFamily lifecycle characteristics M Month of year interview was conducted S State specific variables W Day of week interview was conducted

  13. Estimated Travel Behavior for 1990 individuals can be • determined in the form • Since the NPTS was not conducted as a panel survey, • we first estimate a model of 1990 individuals, and • then apply that model to 1995 individuals in the form • Then we estimated a difference model of change in travel behavior between the 1995 individuals their best estimate • of 1990 behavior Methodology

  14. s.t. change in time at activity "i" between 1995 and 1990 (estimated) Difference Model

  15. TRAVEL TO TIME SPENT AT + - - + - - - - H W S O H W S O Time Savings From Travel Time Savings From Travel Time Savings From Travel Reduced Peak Spreading Big Box Stores Pleasure Oriented Faster Network Hypothesis for Workers

  16. TRAVEL TO TIME SPENT AT + + - + + - H S O H S O Less Discretionary More # of Home-Shop Trips Faster Network Pleasure Oriented Hypothesis for Non Workers

  17. * Indicates significance at 95% confidence level Elasticity of Time with respect to Capacity

  18. Results Due to Highway Capacity Expansion • Workers spend more Time at Home and Other, Less Time at Work and Shop • Non-Workers spend more Time at Home and Other, Less Time at Other • Non-workers take more Home to Shop trips

  19. Conclusions • Overall Travel Times have remained stable while Activity Durations changed significantly • Increase in highway capacity has a small but significant impact on individual’s activity and travel patterns • Effect on Workers and Non-Workers are different

  20. Questions?

  21. Time Budgets and Induced Demand: How Access Affects Activity By David M Levinson Seshasai Kanchi University of Minnesota CTS Research Conference 25th May 2000

  22. Time Budgets and Induced Demand: How Access Affects Activity By David M Levinson Seshasai Kanchi University of Minnesota Symposium on Induced Traffic Research University of California,Berkeley June 8-9, 2000

  23. Time Budgets and Induced Demand: How Access Affects Activity By David M Levinson Seshasai Kanchi University of Minnesota 9th International Association For Travel Behavior Research Conference Gold Coast, Queensland, Australia July 2-7, 2000

  24. Whence Induced Demand: How Access Affects Activity By David M Levinson Seshasai Kanchi University of Minnesota Western Regional Science Association Palm Springs California February 2001

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