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Scott Vincent Masten California DMV Research & Development Branch

Learning to Drive in California: Patterns in Novice Motor Vehicle Crashes and Traffic Violations in the Era of the Graduated Driver Licensing Law. Center for Healthcare Policy and Research Seminar Series. Scott Vincent Masten California DMV Research & Development Branch. Speaker’s Verbal

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Scott Vincent Masten California DMV Research & Development Branch

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  1. Learning to Drive in California: Patterns in Novice Motor Vehicle Crashes and Traffic Violations in the Era of the Graduated Driver Licensing Law Center for Healthcare Policy and Research Seminar Series Scott Vincent Masten California DMV Research & Development Branch
  2. Speaker’s Verbal Disclosure Statement Have you (or your spouse/partner) had a personal financial relationship in the last 12 months with the manufacturer of the products or services that will be discussed in this CME activity? ___ Yes _X_No (If yes, please state disclosures and resolutions)
  3. Educational Objectives for this Seminar To describe how the crash rates of novice drivers change after licensure To identify novice drivers with exceptionally high crash rates after the California graduated driver (GDL) licensing law was implemented To discuss opportunities for reducing crash mortality and morbidity among age 18 and older novices
  4. Why should I care? Over 2.7 million injuries per year Leading cause of death for ages 13-25 Top 5 cause of death for ages 1-44 Motor Vehicle Crashes CDC, WISQARS, 2014
  5. 1.4% All-Age Causes of DeathUnited States, 2010 CDC, WISQARS, 2014
  6. Age 16-19 Causes of DeathUnited States, 2010 27.4% CDC, WISQARS, 2014
  7. 2,500 teen driver deaths (180 California) 1,600 teen passenger deaths (170 California) 10% of all crash fatalities are teens Fatal 16-19-Year-Old CrashesUnited States, Annual FARS; 2000-2009
  8. Crash Rates by Driver AgeUnited States, 2000 Crash rates decrease as age increases Highest rates among teens 16-19 Many teens are just learning to drive (novices)
  9. Novice teen crash rates decrease markedly during the first year They continue to decrease at a slower rate for years Even a little driving experience results in much lower crash rates First Crash IncidenceEach Month After Licensed to Drive Unsupervised
  10. Reduce risk while experience gained Implemented in all U.S. jurisdictions Restrictions on novice teen driving are gradually removed in three stages: Learner Stage May drive only with a licensed adult Intermediate Stage Unsupervised, but driving restrictions: Nighttime Passengers, usually other teens Unrestricted (full) Driving Stage Graduated Driver Licensing (GDL)

  11. Graduated Driver Licensing and Fatal Crashes Involving 16- to 19-Year-Old Drivers

    Scott V. Masten, Robert D. Foss, & Stephen W. Marshall
  12. Design Pooled cross-sectional time series Data Fatality Analysis Reporting System (FARS) Driver fatal crash involvements Passenger vehicles All states & D.C. 1986-2007, quarterly State-age group-quarters Population data from the U.S. Census Nationwide Evaluation of GDL
  13. Analysis Poisson regression with GEEs Separate models ages 16, 17, 18, 19, & 16-19 Control for non-GDL law changes, crude exposure, economic conditions Trend & seasonality adjusted by state & age Adult crash rate covariates - unmeasured confounders Nationwide Evaluation of GDL
  14. Age 16 crashes lower under GDL Age 18 crashes higher under GDL U.S. Teen Fatal Crashes Post-GDL

  15. Evaluation of the California Graduated Driver Licensing (GDL) Program

    Scott V. Masten & Robert A. Hagge Note: Originally completed in 2004; updated data presented here
  16. Implemented July 1998 Applies to all drivers licensed age <18 Learner Stage Min age 15; 15½ starting 2004 6 mo. mandatory learner permit 50 hours supervised practice Intermediate Stage (age ≥16) Nighttime restriction - 12:00am-5:00am for 12 mo. 11:00pm-5:00am starting 2006 Passengers – None < age 20 for 6 mo. 12 mo. starting 2006 Unrestricted (full) Driving Stage Min age 17; automatic at age 18 The California GDL Program
  17. How did CA population-based teen crash rates change after GDL? How did CA driver-basedteen injury crash rates change after GDL? How did CA licensure rates change after GDL? Research Questions
  18. Statewide Integrated Traffic Records (SWITRS) Driver injury crash involvements Passenger vehicles 1985-2011, monthly Population data from the U.S. Census License data from DMV Study Data
  19. Age 18-20 crashes increased after GDL California Crashes, per capita Age 16 crashes decreased after GDL
  20. Age 17-20 increased after GDL California Crashes, per driver No decrease in age 16 crash rates per driver after GDL
  21. Age 18-20 same or increased after GDL California Licensure Rates Age 16-17 licensure decreased after GDL
  22. CA crashes mirror the nationwide GDL study Lower crashes for younger teens Higher crashes for older teens CA licensure rates after GDL: Lower for ages 16-17 Same or higher for ages 18-20 Study Conclusions What’s going on with older CA teens after GDL?

  23. Crash Rates of Teens Delaying Licensure Compared with Those Not Delaying Licensure

    Eric A. Chapman& Scott V. Masten
  24. Nationally, GDL associated with higher 18–19-year-old fatal crash rates (Fell, Jones, Romano & Voas, 2011; Males, 2007; Masten, Foss, & Marshall, 2011; Masten & Hagge, 2003) Possible mechanisms: More 18–19 Novices: Delayed licensure to avoid GDL Lower 18–19 Competency: GDL limits real-world driving experience Study Background
  25. Do CA teens appear to delay licensure to avoid GDL? How do CA teens who delay licensure drive compare to their same-age peers? How do CA teens who delay licensure compare to novices of other ages? Research Questions
  26. Data Random 10% of CA newly-licensed (novices), 1999–2007 (post-GDL) 3-year total & fatal/injury crashes Analyses Age of novice CA licensure Novices vs. same-age peers licensed 1 or 2 years prior Separate Poisson models 18, 19, 20, 21–24, & 25–35 Different-aged novices vs. each other Method
  27. Most novices at 16 or 18 Fewer at 17, suggesting… Delayed licensure until 18 Age of Novice Licensure, 1999-2007
  28. Age 18 Novices vs. Age 18 Experienced Licensed at 18 (avoided GDL) Licensed at 17 (GDL) Licensed at 16 (GDL) Note: Rates adjusted for sex, year, & month of licensure.
  29. Age 19 Novices vs. Age 19 Experienced Licensed at 19 (avoided GDL) Licensed at 18 (avoided GDL) Licensed at 17 (GDL) Note: Rates adjusted for sex, year, & month of licensure.
  30. Experience associated with fewer crashes for all ages… Ages 21-24 Age 20 Age 20+ Novices vs. Age 20+ Experienced Novices of all ages are worse drivers than same-age peers. Ages 25-35
  31. 18 16 17 Even younger novices 19 20 Drop 21-24 25-35 18 novices start out worse than everyone… Novices of Different Ages (Total Crashes) One age group does not fit the pattern Note: Rates adjusted for sex, year, & month of licensure.
  32. 18 19 novices also bad 19 20 Drop 17 16 21-24 25-35 Again 18 novices are worse than everyone Novices of Different Ages (Fatal/Injury) Does this explain the higher 18-19 crash rates after CA GDL? Note: Rates adjusted for sex, year, & month of licensure.
  33. Do CA teens appear to delay licensure to avoid GDL? Yes: Fewer teens licensed at 17 Licensure pops up again at 18 Research Question #1
  34. How do CA teens who delay licensure drive compare to their same-age peers? They have higher crash rates: CA 18 and 19 year-olds who delay licensure crash more than their same-aged peers… But this is true for novices of all ages compared to their same-age peers Research Question #2
  35. How do CA teens who delay licensure compare to novices of other ages? They have higher crash rates: Delaying 18 year-olds have higher total and fatal/injury crash rates than other novices. Delaying 19 year-olds have higher fatal/injury crash rates than other novices. Research Question #3
  36. Some CA teens appear to delay licensure until age 18: No GDL or driver education. 18-19 novices who avoid GDL are worse than ALL other novices, even younger teens Was this a result of implementing GDL? All novices worse than their experienced peers: GDL may benefit novices of all ages. Study Conclusions
  37. Crash and Traffic Violation Rates Before and After Licensure of Novice California Drivers Subject to Different Driver Licensing Requirements Eric A. Chapman, Scott V. Masten, & Kelly K. Browning
  38. When novice teens begin to drive unsupervised their crashes increase radically, even under GDL programs (Lewis-Evans, 2010; Mayhew et al., 2003; VicRoads, 2008) Crash rates decrease dramatically within the first months of licensure, but remain high vs. older novices (Lewis-Evans, 2010; Masten & Foss, 2010; Mayhew et al., 2003; Twisk & Stacey, 2007; VicRoads, 2008) Inexperience may cause high initial crash rates; teen rates may remain elevated because of overconfidence (Ericsson, Krampe, & Tesch-Römer, 1993) Study Background
  39. How do crash and traffic violation rates of novice CA 16–17-year-old drivers licensed under GDL change over time? How do the rates for novice drivers age 18 and older not licensed under GDL change over time? How do the types of traffic violations vary during the course of licensure? Research Questions
  40. Data All novices licensed in CA at age 16 or 17 (2001-2007) 10% sample of all age 18 to 35 novices (2001-2007) 3-year post-licensure crashes and traffic violations Traffic violations categorized as inexperience-related vs. overconfidence-related Analyses Length learner permits are held by age Crash and traffic violation rates over time Overall & subtypes (e.g., fatal/injury, inexperience) Separate Poisson models 16, 17, 18, 19, 20, 21–24, 25–35 Method
  41. Majorities of age 16 (57%) and age 17 (73%) hold learner permits longer than the required 6 months 31% of age 16 and 49% of age 17 hold permits for 9+ months Majorities of age 18+ novices hold learner permits less than 6 months Learner Permit Holding by Age
  42. Peak rates typically 2nd or 3rd month Age 18+ ramp-up of crashes before licensure Total Crash Rates Crash rates for all novices decrease most during 1st year of driving
  43. Pre-licensure rates highest for age 18+ Fatal/Injury Crash Rates Age 18 and 19 novices initially crash more than younger novices
  44. Crash rates of most novices are highest immediately after licensure They decline quickly during their 1st year Then decline slower for the 2nd and 3rd years Just like classic learning curves Crash Rate Findings
  45. Post-licensure crashes are higher for some age 18+ novices than those for ages 16–17 Pre-licensure crash rates for age 18+ novices ramp up immediately before licensure Suggests they try to learn to drive during a very short time period Contrary to good learning methods (spaced practice) 70% of age 16–17 novices are crash-free for the first 3 years of licensure Crash Rate Findings (cont)
  46. Wow Age 18+ violations highest during 1st year or pre-license Total Traffic Violation Rates Traffic violations for age 16 and 17 novices peak long after their crashes, around the time when they are age 18
  47. Age 16-17: inexperience & overconfidence violations peak after crashes, when they turn age 18 Inexperience Age 18+: inexperience and overconfidence violations peak 1st year of licensure, when crashes peak too Inexperience vs. Overconfidence Violations Overconfidence
  48. Age 16–17 novices’ traffic violation rates peak long after their crashes peak (when age 18) Violation rates for age 18+ novices peak during their 1st year of licensure. Inexperience and overconfidence violations typically peak around the same time 45% of age 16–17 novices are traffic violation-free for the first 3 years of licensure Traffic Violation Rate Findings
  49. Age 16–17 novices typically hold learner permits for longer than minimum 6 mo. Older CA novices appear to rush learning to drive; do not hold permits very long Novices driver crash rates for most ages follow a classic learning curve Novice driver violation rates do not follow a classic learning curve—proxy for exposure Study Conclusions
  50. Review of Educational Objective #1 To describe how the crash rates of novice drivers change after licensure Pattern follows classic learning curve Highest immediately after licensure Decrease dramatically during the 1st year Decrease at a slower rate subsequently
  51. Review of Educational Objective #2 To identify novice drivers with exceptionally high crash rates after the California graduated driver (GDL) licensing law was implemented Age 18-20 crashes increased after GDL Age 18-19 crash rates now higher than all other novices, even younger teens
  52. Review of Educational Objective #3 To discuss opportunities for reducing crash mortality and morbidity among age 18 and older novices Given that age 18+ novices appear to cram learning to drive into a short period… Maybe they would benefit from minimum learner permit holding periods Given that age 18+ novices are also worse than their experienced peers… Maybe they would benefit if GDL was extended to them, particularly for ages 18-20
  53. Scott V. Masten Scott.Masten@dmv.ca.gov Thank you!Questions & Discussion
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