Teenage drivers more reckless with young male passenger in front seat
August 26, 2005
Teenage drivers-both males and females-were more likely to tailgate
and exceed the speed limit if there was a teenage male passenger
in the front seat, according to a study by the National Institute
of Child Health and Human Development of the National Institutes
Conversely, male teenagers were less likely to tailgate or exceed
the speed limit when a teenage female was in the front passenger
In addition, female teen drivers were slightly more likely to
tailgate if there was a female teen passenger in the vehicle with
The study was published on-line in Accident Analysis and Prevention and
will appear in a future edition of that journal.
This study provides information that will be useful for officials
in devising teen licensing standards, said NICHD Director Duane
Alexander, M.D. The findings indicate that teen risky driving
increases in the presence of teen passengers, particularly male
teen passengers. But more important, the finding should remind
teens-and the adults who care about them-that they need to drive
safely, regardless of who is in the passenger seat.
The study was unable to determine why the presence of teen males
increased the likelihood of speeding and tailgating, said the studys
first author Bruce G. Simons-Morton, Ed.D., M.P.H, Chief of NICHD’s
Prevention Research Branch.
Crash rates for 16- and 17-year-old drivers are higher in the
presence of teen passengers, Dr. Simons-Morton and his colleagues
wrote. However, researchers do not understand the reasons for these
higher crash rates. Dr. Simons-Morton and colleagues at the survey
research firm Westat undertook the current study to learn how the
presence of teen passengers might affect teens driving behavior.
To conduct the study, the researchers positioned observers at
the parking lot exits of 10 high schools in the suburban Washington,
D.C. area. The observers took notes on the make and model of the
departing vehicles, as well as the age and gender of the driver
and passengers. A second group of observers was stationed ½ to ¾ of
a mile away from the parking lot, and used video recording equipment
and a laser-assisted radar device to measure traffic flow. This
second set of observers charted the speed of the vehicles and measured
vehicle headway, an indication of how closely vehicles follow the
vehicles in front of them. The study authors defined vehicle headway
as the time (in seconds) between vehicles as they passed a fixed
point in the roadway.
More than 3000 passing vehicles were recorded at the second site.
Of these, 2251 were vehicles in general traffic, and 471 were teen
drivers (245 male and 226 female). No passengers were present in
232 of the teen vehicles, and one or more passengers were present
in 239 of the teen vehicles.
On average, teens drove 1.3 miles an hour faster than the general
traffic. Moreover, the average headway for teen drivers was about
.17 seconds shorter than for the general traffic (about 10 feet
less at 40 miles an hour).
Both male and female teenage drivers were most likely to drive
faster than the general traffic and to allow shorter headways if
there was a male teenage passenger in the car. In fact, when a
male passenger was in the vehicle, a quarter of teenage drivers
exceeded the speed limit by at least 15 miles an hour.
(A graph showing the percentage of teenagers driving over 15 miles
an hour is posted at http://www.nichd.nih.gov/new/releases/teenage_drivers_statistics.cfm.)
Similarly, both male and female teens drove faster and allowed
shorter headways in the presence of a male teenage passenger when
compared to teens who had either no passengers or a female teen
passenger. However, teenage males allowed longer headways in the
presence of female passengers.
On average, headways were .3 seconds shorter for male teens drivers
with male teen passengers, and .15 seconds shorter for female teen
drivers with female teen passengers.
At typical driving speeds of around 40 mph, a 0.3 [seconds] difference
is equivalent to traveling slightly more than one car length closer
to the vehicle ahead, the authors wrote.
In the article, the study authors explained that although they
studied vehicle headway and speed independently, these two factors
are probably related. Close following headways may constrain speed;
fast driving may result in close following, they wrote.
For this reason, the authors charted the proportion of teens engaging
in some form of risky driving, which they defined as either driving
with a headway of less than 1 second, and speeds 15 or more miles
above the posted speed limit.
According to these criteria, of the 14.9 percent of teen males
engaging in risky driving, 21.7 percent had a male teen passenger
in the vehicle. In contrast, only 5.5 percent of teen male drivers
showed risky driving behavior in the presence of a female passenger.
Of the 13.1 percent of teen female drivers showing risky driving
behavior, 12.9 percent had a male teen passenger, and 15.5 percent
had a female passenger. Dr. Simons-Morton said that most cases
of risky driving in this 15.5 percent of risky teen female drivers
were due to short headways.
Dr. Simons-Morton noted that the current study could not identify
why teens were more likely to engage in more risky driving behavior
in the presence of teen passengers. Teen passengers may distract
the driver or change the drivers attitude or emotion in ways that
are not yet clear. To find answers, he and his colleagues are currently
designing a study that will involve placing electronic monitoring
equipment in vehicles with teen drivers. After learning the reasons
for the risky behavior, researchers can then work to develop ways
to prevent it.
Until answers become available, Dr. Simons-Morton cautioned parents
and teens to be aware of a tendency that teens appear to have toward
risky driving when other teens are in the vehicle with them, and
to be extra vigilant against unsafe driving under these conditions.
The NICHD is part of the National Institutes of Health (NIH),
the biomedical research arm of the federal government. NIH is
an agency of the U.S. Department of Health and Human Services.
The NICHD sponsors research on development, before and after
birth; maternal, child, and family health; reproductive biology
and population issues; and medical rehabilitation.
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Medical Research Agency — is comprised of 27 Institutes
and Centers and is a component of the U. S. Department of Health
and Human Services. It is the primary Federal agency for conducting
and supporting basic, clinical, and translational medical research,
and investigates the causes, treatments, and cures for both common
and rare diseases. For more information about NIH and its programs,
This is a NIH news release. The original version appears here