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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

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

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)


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


Motor vehicle crashes

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


All age causes of death united states 2010

1.4%

All-Age Causes of DeathUnited States, 2010

CDC, WISQARS, 2014


Age 16 19 causes of death united states 2010
Age 16-19 Causes of DeathUnited States, 2010

27.4%

CDC, WISQARS, 2014


Fatal 16 19 year old crashes united states annual

  • 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


Crash rates by driver age united states 2000
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)


First crash incidence each month after licensed to drive unsupervised

  • 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


Graduated driver licensing gdl

  • Reduce risk while experience gained year

  • 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)


Graduated driver licensing and fatal crashes involving 16 to 19 year old drivers

Graduated Driver Licensing and Fatal yearCrashes Involving 16- to 19-Year-Old Drivers

Scott V. Masten, Robert D. Foss, & Stephen W. Marshall


Nationwide evaluation of gdl

  • Design year

  • 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


Nationwide evaluation of gdl1

  • Analysis year

  • 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


U s teen fatal crashes post gdl

Age 18 crashes higher under GDL

U.S. Teen Fatal Crashes Post-GDL


Evaluation of the california graduated driver licensing gdl program

Evaluation of the California Graduated Driver Licensing (GDL) Program

Scott V. Masten & Robert A. Hagge

Note: Originally completed in 2004; updated data presented here


The california gdl program

  • Implemented July 1998 (GDL) Program

  • 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


    Research questions

    • How did CA (GDL) Programpopulation-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


    Study data

    • Statewide Integrated Traffic Records (GDL) Program(SWITRS)

      • Driver injury crash involvements

      • Passenger vehicles

      • 1985-2011, monthly

    • Population data from the U.S. Census

    • License data from DMV

    Study Data


    California crashes per capita

    Age 18-20 crashes increased after GDL (GDL) Program

    California Crashes, per capita

    Age 16 crashes decreased after GDL


    California crashes per driver

    Age 17-20 increased after GDL (GDL) Program

    California Crashes, per driver

    • No decrease in age 16 crash rates per driver after GDL


    California licensure rates

    Age 18-20 same or increased after GDL (GDL) Program

    California Licensure Rates

    Age 16-17 licensure decreased after GDL


    Study conclusions

    Study Conclusions

    • What’s going on with older CA teens after GDL?


    Crash rates of teens delaying licensure compared with those not delaying licensure

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

    Eric A. Chapman& Scott V. Masten


    Study background

    • 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


    Research questions1

    Research Questions


    Method

    • Data fatal crash rates

      • 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


    Age of novice licensure 1999 2007

    Most novices fatal crash rates at 16 or 18

    Fewer at 17, suggesting…

    Delayed licensure until 18

    Age of Novice Licensure, 1999-2007


    Age 18 novices vs age 18 experienced
    Age fatal crash rates 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.


    Age 19 novices vs age 19 experienced
    Age 19 fatal crash rates 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.


    Age 20 novices vs age 20 experienced

    Experience associated with fewer crashes for fatal crash rates 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


    Novices of different ages total crashes

    18 fatal crash rates

    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.


    Novices of different ages fatal injury

    18 fatal crash rates

    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.


    Research question 1

    Do CA teens appear to delay fatal crash rates licensure to avoid GDL?

    Yes:

    • Fewer teens licensed at 17

    • Licensure pops up again at 18

    Research Question #1


    Research question 2

    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


    Research question 3

    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


    Study conclusions1

    Study Conclusions


    Eric a chapman scott v masten kelly k browning

    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


    Study background1

    • 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


    Research questions2

    • 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


    Method1

    • Data 16–17-year-old drivers licensed under GDL change over time?

      • 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


    Learner permit holding by age

    Learner Permit Holding by Age


    Total crash rates

    Peak rates typically 2 permits nd 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


    Fatal injury crash rates

    Pre-licensure rates highest for age 18+ permits

    Fatal/Injury Crash Rates

    Age 18 and 19 novices initially crash more than younger novices


    Crash rate findings

    Just like classic learning curves

    Crash Rate Findings


    Crash rate findings cont

    • 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)


    Total traffic violation rates

    Wow than those for ages 16–17

    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


    Inexperience vs overconfidence violations

    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


    Traffic violation rate findings

    • Age after crashes, when they turn 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


    Study conclusions2

    • 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


    Review of longer than minimum 6 mo.

    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


    Review of longer than minimum 6 mo.

    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


    Review of longer than minimum 6 mo.

    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


    Thank you questions discussion

    Scott V. Masten longer than minimum 6 mo.

    [email protected]

    Thank you!Questions & Discussion


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