TEENAGE DRIVER CRASHES -- CARRYING PASSENGERS AS A RISK FACTOR

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TEENAGE DRIVER CRASHES -- CARRYING PASSENGERS
AS A RISK FACTOR
Li-Hui Chen, MS, Ph.D. Assistant Scientist
Johns Hopkins School of Public Health
Center for Injury Research Policy
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Readings

• Carrying passengers as a risk factor for crashes
  fatal to 16- and 17-year-old drivers
• Reducing fatal crash risk among teenaged drivers
• Graduated licensing a blueprint for North
  America

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Learning Objectives

• Understand the scope of MV injury for teenage
  drivers
• Learn about the risk to teenage drivers of
  carrying passengers
• Learn about the GDL system

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Performance Goals

• Be able to describe the importance of MV injury
  for teenagers
• Be able to describe the risk of carrying
  passengers for teen driver
• Be able to describe the ideal GDL system

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Background

• For U.S. teens, MV crashes
• are the leading cause of death, accounting for
  36 of all deaths
• have a much higher rate than for older drivers

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Background--Haddon Matrix
Phases Factors Factors Factors
Phases Human Vehicle Environment
Precrash Carrying Passengers
Crash
Postcrash

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BackgroundGDL System

• Lets teen drivers earn experience step by step
  and in a less risky environment

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Background--Central framework for GDL

• Three stages
• Supervised learners period
• Intermediate license
• Full license

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BackgroundCurrent GDL adoption in the U.S.

• 30 states had adopted full graduated licensing
  systems
• 14 states had some passenger restrictions

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Methods--Data

• FARS All fatal crashes in the U.S.
• GES Sample of police reported crashes in the
  U.S.
• NPTS Survey of travel patterns in the U.S.

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Methods--Analysis

• Risk of death per 10 million trips
• Risk of death per 1000 crashes
• Relative risk and confidence intervals

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Results

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Results
Trip-Based Risks for Teenaged Driver Deaths Trip-Based Risks for Teenaged Driver Deaths Trip-Based Risks for Teenaged Driver Deaths Trip-Based Risks for Teenaged Driver Deaths Trip-Based Risks for Teenaged Driver Deaths Trip-Based Risks for Teenaged Driver Deaths Trip-Based Risks for Teenaged Driver Deaths Trip-Based Risks for Teenaged Driver Deaths
6AM-959 PM 6AM-959 PM 10-1159 PM 10-1159 PM 10-1159 PM 12-559 AM 12-559 AM
Passenger Present Passenger Present Passenger Present Passenger Present Passenger Present Passenger Present Passenger Present
No Yes No Yes No No Yes
DR 1.24 2.20 3.26 6.37 14.20 14.20 21.88
RR - 1.77 - 1.95 - - 1.54

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Results
Driver Deaths (aged 16-17) per 1,000 Crashes Driver Deaths (aged 16-17) per 1,000 Crashes Driver Deaths (aged 16-17) per 1,000 Crashes Driver Deaths (aged 16-17) per 1,000 Crashes Driver Deaths (aged 16-17) per 1,000 Crashes Driver Deaths (aged 16-17) per 1,000 Crashes
Age and Number of Passengers Age and Number of Passengers Age and Number of Passengers Age and Number of Passengers Age and Number of Passengers
Aged 13-19 Aged 13-19 Aged 20-29 Aged 20-29
None 1 gt2 1 gt2
DR 1.44 2.08 2.46 3.55 3.90
RR - 1.45 1.71 2.47 2.71

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Results
Teenaged Driver Deaths per 1,000 Crashes Teenaged Driver Deaths per 1,000 Crashes Teenaged Driver Deaths per 1,000 Crashes Teenaged Driver Deaths per 1,000 Crashes Teenaged Driver Deaths per 1,000 Crashes Teenaged Driver Deaths per 1,000 Crashes Teenaged Driver Deaths per 1,000 Crashes
Sex and Number of Passengers Sex and Number of Passengers Sex and Number of Passengers Sex and Number of Passengers Sex and Number of Passengers Sex and Number of Passengers
Female Female Male Male
None 1 gt2 1 gt2 Both Sex
DR 1.44 1.56 1.59 2.54 3.19 2.63
RR - 1.08 1.11 1.76 2.22 1.83

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Results-Summary

• Fatal crash rates for drivers aged 16-17
  increased with the number of passengers for both
  day and night
• Crashes are more likely to be fatal in the
  presence of male, teen, and age 20-29 passengers

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Discussion--Possible explanations

• Dangerous driving behaviors
• Distraction
• Alcohol involvement

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Discussion--Limitations

• Unable to control alcohol
• Do not have information on age of passengers in
  travel pattern

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Conclusions

• Restrictions on carrying passengers should be
  considered for inclusion in graduated licensing
  systems for young drivers

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Further Studies

• Age of passengers
• The relationship to alcohol use
• Why carrying passengers increases risk