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Status Report, Vol. 34, No. 10 | SPECIAL ISSUE: GRADUATED LICENSING | December 4, 1999 Subscribe

Teen passenger restriction will save lives, study predicts

The new licensing systems in a number of states give 16 year-olds a best/worst deal. They finally get their licenses, but they can't give their friends a ride.

What may seem punitive — restricting teen passengers — is actually a way to save lives. New research from Johns Hopkins University and the Institute "suggests passenger restrictions for beginners could mean hundreds fewer deaths each year," says Institute senior vice president Allan Williams

The research shows that when teenagers drive with teen passengers, their already high crash risk greatly increases (see "Presence of passengers increases teenage drivers' risk of crashing" Feb. 6, 1999). Nine U.S. states — California, Delaware, Georgia, Indiana, Massachusetts, New Jersey, New Mexico, Oregon, and Wisconsin — plus New Zealand impose some type of passenger restriction.

Such restrictions are among the more controversial components of graduated licensing. Some argue the restrictions are inconvenient and will be routinely violated. Others say compliance may put more young drivers out on the road, thus increasing crash risk.

"Passenger restrictions in the United States are new, and we won't know their actual effects for several years," Williams notes. "But because state legislators are considering them, we wanted to estimate their net effects." To do this, researchers first analyzed 1990 fatality statistics, looking at all types of road deaths involving teen drivers including pedestrians, bicyclists, motorcyclists, and people in vehicles driven by teenagers or struck by teen drivers. The death rate for 16- and 17-year-old drivers transporting only passengers younger than 20 was almost 4 times the rate for drivers ages 16-17 without passengers.

The researchers then estimated what would happen if 16- and 17-year-old drivers throughout the United States were prohibited from getting behind the wheel with passengers younger than 20 (in the absence of an adult), based on different choices available to the teenage passengers — driving themselves, giving up the trip, going with an older driver, or ignoring the restriction.


Estimated lives saved per year when passenger restrictions for new 16-and 17-year-old drivers change the way teenagers travel

350 lives saved if teen passengers make the following transportation changes:

  • 10% violate restriction by going with young driver anyway
  • 10% drive themselves
  • 30% don’t go
  • 50% go with older drivers (18+)

275 lives saved if teen passengers make the following transportation changes:

  • none violate restriction by going with young driver anyway
  • 100% drive themselves

150 lives saved if teen passengers make the following transportation changes:

  • 50% violate restriction by going with young driver anyway
  • 30% drive themselves
  • 20% go with older drivers (18+)

60 lives saved if teen passengers make the following transportation changes:

  • 80% violate restriction by going with young driver anyway
  • 10% drive themselves
  • 10% go with older drivers (18+)

Putting more young drivers alone on the road while decreasing the number of drivers with teenage passengers is estimated to substantially reduce deaths. For example, 38 percent fewer fatalities would be expected (275 lives saved) if all drivers obeyed the law and all passengers drove by themselves. None of the passengers would give up their trips or go with older drivers.

If only half the drivers obeyed the law, death reductions would be 20 to 30 percent, depending on passengers' actions. And if 20 percent of drivers complied, a 9 percent death reduction is estimated.

"Of course, some teenagers will ignore the rule and take their friends along," Williams continues. "Even if only half the drivers obeyed the restrictions, we could expect a substantial reduction in deaths."

Johns Hopkins researcher Li-Hui Chen explains that the crash risk associated with transporting teen passengers is so high that "even with low compliance, teen passenger rules are likely to save lives. When you consider that the road user death rate for 16-17-year-old drivers with passengers younger than 20 is 4 times the rate with no passengers, there would be a benefit even if all of the teenage passengers drove themselves."

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