Number 313 June 2006

Traffic Safety Facts

Traffic Tech – Technology Transfer Series

National Evaluation of Graduated Driver 

Licensing Programs

Background

The crash rate per mile driven for 16-year-old 

drivers is almost 10 times the crash rate for drivers 

ages 30-59 and more than twice the rate of 18- to 

19-year-old drivers. Graduated Driver Licensing 

(GDL) programs have become an increasingly popular 

approach to managing the serious problem of high 

rates of fatal and nonfatal crashes among beginning 

drivers.

These programs vary by State, but most are designed 

to provide novice drivers the opportunity to gain 

driving experience in less risky circumstances. 

They achieve this objective using various provisions. 

The most common provisions are: raising the age of 

full licensure, requiring more hours of supervised 

driving, restricting nighttime driving, and limiting 

the number of unrelated passengers permitted in 

the vehicle.

A typical GDL program has three phases: a learner’s 

permit with supervised training, an intermediate 

period where unsupervised driving is limited to less 

hazardous situations, and finally a full unrestricted 

license phase. By the end of 2004, 41 States and the 

District of Columbia had instituted some form of GDL 

that included two phases prior to full licensure.

Prior evaluation studies of GDL programs comparing 

fatal crash involvement rates before and after GDL 

implementation in individual States have reported 

overall reductions in crash rates of newly licensed 

drivers ranging from 11 percent to 32 percent. 

Because the various State GDL programs incorporate 

different components, and because often several 

components are introduced simultaneously, separate 

evaluation of individual GDL components has not 

been feasible.

However, it is feasible to examine which types of GDL 

programs are associated with the greatest reductions 

in crashes in newly licensed drivers. This study was 

undertaken to determine both the overall impact of 

GDL programs and the types of GDL programs that 

are effective in reducing crashes.

Approach

This study analyzed fatal crash rates for 16-year-old 

drivers compared to drivers ages 20-24 and 25-29 (for 

whom the GDL program did not apply) by the number 

and type of GDL provisions. The seven components 

were: minimum age of 15 1⁄2 for obtaining a learner 

permit; minimum three-month waiting period after 

obtaining a permit before applying for an intermediate 

license; minimum 30 hours of supervised driving; 

minimum age of 16 for obtaining an intermediate 

license; minimum age of 17 years for obtaining a 

full license; nighttime restriction; and passenger 

restriction.

Findings

The following figure (overleaf) shows the relationship 

between the percent change in annual fatal crash 

involvement rates and the total number of program 

components, regardless of which specific components 

are included. Percent changes show differences among 

GDL programs with one component compared to 

none, two components compared to none, etc. 

For 16-year-old drivers (represented by filled 

diamonds), one can see that programs with five or 

more components were associated with a significant 

reduction in fatal crash involvements when compared 

to periods when none of the components were in effect. 

It is also noteworthy that neither the 20-24 nor the 25-

29 comparison driver age group experienced similar

U.S. Department of Transportation 400 Seventh Street, SW, Washington, DC 20590

National Highway Traffic Safety Administration
400 Seventh Street, SW., NTI-130

Washington, DC 20590

TRAFFIC TECH is a publication to disseminate

information about traffic safety programs, including

evaluations, innovative programs, and new publications. Feel free to copy it as you wish. If you would

like to receive a copy, contact Patricia Ellison Potter,

Ph.D., Editor, fax 202-366-7096, e-mail: patricia.ellisonpotter@nhtsa.dot.gov.

Percent Change in Annual Fatal Crash Rate in Relation to Number of GDL Program Components, Compared to 

Having None of Seven Components, for Drivers Age 16, 20-24, and 25-29; United States, 1994-2004.

Vertical Lines Represent 95-Percent Confidence Limits. Percent Change in Annual Fatal Crash Involment Rates

-35%

-30%

-25%

-20%

-15%

-10%

-5%

0%

5%

10%

15%

Driver Age

16

20-24

25-29

One Two Three Four Five Six/Seven

Number of GDL Components (in any combination)

declines in fatal crash involvement rates when these 

GDL programs were in effect compared to when they 

were not in effect. 

Among existing programs that were sufficiently 

common for analysis, significant reductions were 

associated with programs having five or more 

components, including age requirements and:

n a waiting period of at least three months before 

the intermediate stage, 

n a restriction on nighttime driving, and either

n thirty or more hours of supervised driving or

n a restriction on carrying passengers. 

Overall, the study found an 11-percent reduction in 

fatal crash involvements after the GDL programs were 

adopted. This overall 11-percent reduction reflects the 

combined results for all three-stage GDL programs, 

and includes States with relatively weak programs, 

thus diluting the overall effect. Even with this dilution, 

an 11-percent reduction in fatal crash involvements 

for 16-year-olds is substantial, and provides a strong 

justification for States to consider adopting these 

programs.

How To Order

For a copy of National Evaluation of Graduated Driver 

Licensing Programs (16 pages) write to the Office of 

Behavioral Safety Research, NHTSA, NTI-130, 400 

Seventh Street SW., Washington, DC 20590, or send 

a fax to 202-366-7096, or download from www.nhtsa.

dot.gov. The findings reported herein will also be 

published in the journal Pediatrics, by authors Li-Hui 

Chen, Susan P. Baker, and Guohua Li. Paul J. Tremont, 

Ph.D. was the NHTSA project officer.