1. The Transition to Unsupervised Driving1

2. Background Motor vehicle crashes are the leading cause of
death for teenagers in the United States
In 2009, 3,466 teenagers (ages 13-19) were
killed in motor vehicle crashes
The economic cost of crashes involving young
drivers is over $34B each year

3. Graduated Driver Licensing
GDL laws vary widely, but all 50 states and DC have some form
Optimal GDL laws feature a 3-tiered approach:
Supervised (learner’s permit)
Restricted unsupervised (e.g., nighttime and passenger restrictions)
Full license
GDL laws allow teen drivers to gain experience behind the
wheel while controlling exposure to risks such as:
Distracting passengers
Nighttime driving
Use of electronic devices
Largely credited for 42% reduction in fatal crashes of
16-year-old drivers since 1996

4. The Problem Parents and other supervisors during the learner’s
permit stage generally do a good job creating a
safe in-car environment
Crashes are rare during this first phase
However, crash rates increase 12 times when teens
first begin to drive unsupervised, and teens are 50
percent more likely to crash in their first month of
driving than they are after getting a year of experience
The specific reasons behind this sharp increase
in crash risk are not well understood

5. GDL Stage I: The Permit
Teens can only operate a motor vehicle with a fully-
licensed driver in the front passenger seat
Stage I was examined in previous AAA Foundation
research (Goodwin et al., Oct. 2010) which found:
Parents created a safe in-car environment during this stage and incidents were rare
Most of the driving experience teens got was under benign conditions and in routine situations
Teens drove less during Stage I than previously assumed: 1.60 hours/week, spread over 3.2 days
Parental instruction was generally quite basic; training in “higher-order” concepts was rare

6. GDL Stage II: Key Questions
How do the driving behaviors of newly-
unsupervised teens change when they obtain a
restricted (provisional) license?
How do the nature of incidents and the driving
environment (internal and external) change when
teens begin to drive unsupervised?
What insight can be gained into the 12-fold crash
rate increase seen during the first months of
unsupervised driving?
How can parents better prepare their teens to be
solo drivers?

7. UNC Highway Safety Research Center
The Study
Published October 2011
Prepared by:
Arthur Goodwin
Robert Foss
Natalie O’Brien
UNC Highway Safety Research Center
Available online at

8. Method Recruited 50 families in North Carolina as
teens applied for learner’s permit
Following completion of October 2010 study
on parental supervision during Stage I, 38
families agreed to continue participating
once teen obtained intermediate license

9. Method (continued) Installed cameras (triggered by change in g-forces)
to capture video clips of the cabin and immediate
surroundings in front of and behind vehicle:
Coded and analyzed nearly 6,000 clips capturing
triggering events (e.g., hard braking, swerving,
sudden acceleration)
Compared these to 1,750 clips from the initial study
(Stage I) that featured the 38 subjects who continued to
participate
Naturalistic – no attempt made to alter behavior of the
study participants
Cameras installed for four months in Stage I, and
six months in Stage II

10. Key Findings and Observations:
Internal Driving Environment
Parent or adult were in the car 3% of Stage II clips
compared with 99% of clips during Stage
Percentage of clips showing young passengers in car
didn’t change; however:
Stage I passengers were mainly siblings
Stage II passengers were often peers
Driver belt usage remained high (99% of Stage I and 98%
of Stage II clips); front passenger belt use declined slightly
Likelihood of loud music seven times higher in Stage II
than Stage I
One in six Stage II clips had music loud enough
to be distracting or mask the sound of horns/sirens

11. Key Findings and Observations:
External Driving Environment
Regardless of license type, most clips were recorded
in the afternoon; however:
Night driving clips (9 pm – 5 am) were more than
twice as likely during Stage II than Stage I
Stage I clips were most likely to be recorded on
weekends; in Stage II they were spread evenly
throughout the week
A greater percentage of Stage II clips occurred in
darkness (21% vs. 17% in Stage I)
Stage II clips 60% more likely to involve wet or
rainy conditions compared to Stage I

12. Key Findings and Observations:
Triggering Events/Incidents
Stage I clips more likely to be triggered by hard
acceleration with Stage II clips more often resulted from
right turns
Otherwise, triggering events generally similar
Few, if any, differences in maximum g-forces were
recorded during Stage I & Stage II triggering events
Judgment errors and deliberately risky maneuvers
became more common once teens began driving
unsupervised
A relatively small number of teens accounted
for many of the recorded incidents

13. Discussion & Recommendations
Driving conditions appear to change between Stages I & II
More clips recorded at night and in rainy conditions once
teens began to drive unsupervised
Teens may not be adequately prepared for this change:
Stage I study found that most supervised practice occurred
during the day and in good weather; more practice under
varying conditions is therefore needed
Most (65%) of Stage II clips showed no passengers in the
vehicle; however:
Teens were more likely to be carrying friends during Stage II,
and studies show higher crash rates under such circumstances
Parents should enforce their state’s GDL passenger
restrictions (or impose their own)

14. Discussion & Recommendations
Parents generally absent from Stage II clips ( they were present in only 3%!)
Remember: just because teens can drive solo with an intermediate license doesn’t mean parents need to disappear or end the training and supervision process
Parents can, and should, stay involved in their teen’s driving
Significant jump in the likelihood of potentially-distracting music during Stage II suggests that teens should be made aware of the hazards associated with loud music
Notably risky or worrisome incidents were relatively rare during both stages, and only a few differences in behavior were observed when teens began driving unsupervised

15. Next Steps
Subsequent report will examine certain key issues in greater detail, such as the nature and prevalence of teen distracted driving, and the influences on teen driving that passengers are observed to have.

16. For more information, go to:
AAAFoundation.org

17. Established by AAA in 1947, the AAA Foundation for Traffic Safety is a 501(c)(3) not-for-profit, publicly-supported charitable educational and research organization. Dedicated to saving lives and reducing injuries on our roads, the Foundation’s mission is to prevent crashes and save lives through research and education about traffic safety. The Foundation is supported by donations from AAA/CAA Clubs, AAA/CAA members, and other organizations associated with AAA/CAA.