The first long-term study of graduated licensing gives a detailed look at how this approach works to reduce the risks while teenagers learn how to drive and get their initial experience behind the wheel. The study, conducted in Nova Scotia, is the first to investigate what each licensing stage in a graduated system contributes to safety. A key finding is that crash reductions among young beginning drivers occur in both the learner and intermediate stages.
The first six months of the learner stage are when researchers found the biggest crash reductions. Another research finding is that the benefits of graduated licensing for teenagers don't come at the cost of higher crash rates later on.
Graduated licensing was adopted in Nova Scotia in 1994, before many U.S. states began considering such an approach. "Because the Nova Scotia program has been in place a few years, it's one of the first opportunities we've had to look at effects over a longer period," Dan Mayhew of Canada's Traffic Injury Research Foundation explains. Mayhew is the lead author of the new study.
The licensing program, which applies to new drivers of all ages (not just teenagers), consists of a six-month learner stage followed by a 24-month intermediate licensing stage. Learners must be accompanied by an experienced driver at all times, and no other passengers are allowed. Learners advance to the intermediate stage after passing a road test, and they can advance sooner if they take driver training. Then, for the next two years, intermediate license holders may drive unsupervised except between midnight and 5 a.m.
This system has attracted support among both parents and teenagers in Nova Scotia (see "Nova Scotia parents and teenagers support graduated licensing," Dec. 27, 1997).
Crashes drop by half
The short- and long-term effects of Nova Scotia's licensing restrictions were evaluated by comparing the numbers of crashes per licensed driver for beginners during the first years of graduated licensing with crash rates for beginners who got their licenses under the prior system. The researchers looked separately at drivers 16 or 17 years old (younger drivers are at higher risk) and drivers who were 18 and older.
The biggest effects were during the first six months of driving for beginners who got their learner's permits when they were 16 or 17 years old. The decline in crashes for this group during this period was 51 percent. Most of the new drivers were supervised under the graduated system, whereas under the prior licensing system more of them already were fully licensed and allowed to drive unsupervised.
The benefits continued during the intermediate stage of graduated licensing, when beginners were allowed to drive unsupervised except late at night. However, the crash reductions were smaller than during the first six months.
Among drivers initially licensed at 16 or 17, crash rates declined 9 percent in the first year and 11 percent in the second year of the intermediate stage. These reductions were statistically significant, and most of the benefits were due to the night driving restriction, which reduced crashes during the restricted hours by about half.
Crash rates were 4 percent higher during the year after drivers could graduate to full licensure status. However, "this small change wasn't statistically significant," says Institute chief scientist Allan Williams. "Some people have been concerned that crash rates might go up once teens get their full licenses because they didn't get as much experience behind the wheel during the learner and intermediate stages. But this didn't happen. There wasn't any significant increase among the younger new drivers, those who were 16 or 17 years old when they began the process of getting a license."
Crashes per 100 drivers per year in Nova Scotia before and after graduated licensing
Different results for older drivers
The patterns were different for novices who got either their learner's permits or licenses at age 18 and older. Crash rates for these drivers were reduced 31 percent during the learner stage, but during the first year of the intermediate stage there was no difference in crash rates for these older beginners compared with drivers who got their licenses under the prior system. During the second year of the intermediate stage and the first year following graduation from the system, crashes increased for drivers 18 and older.
More research is needed to understand the characteristics of older beginning drivers and why the benefits of graduated licensing appear much more limited for this group. However, almost all graduated systems in U.S. states apply to 16 and 17 year-olds only — not beginners 18 and older. The younger group accounts for most of the novice drivers, and they have the highest crash risk.
No benefit of driver education
Another factor the researchers considered was the effect of driver education. Nova Scotia allows beginners to advance from the learner stage to the intermediate licensing stage in three months instead of six if they complete a driver education course. Crash rates for licensed drivers who took such courses and received the time discount were significantly higher than rates for drivers who didn't take driver education. A similar effect was found in an evaluation of Ontario's graduated licensing program.
"So there's no evidence that formal driver education justifies a time discount, and the practice of allowing discounts might actually diminish the safety effects of graduated licensing," Mayhew points out. This finding is consistent with other scientific evaluations of driver education, which indicate these courses don't reduce crash risk among beginners (see "Driver education does not equal safe drivers," Jan. 11, 1997).
Ways to strengthen the program
Nova Scotia's program is successful, but its success would likely be greater if the province adopted a stronger version of graduated licensing — in particular, a night driving restriction that began earlier. Most nighttime crashes involving teenage drivers occur between 9 p.m. and midnight, but the restriction on beginning drivers in Nova Scotia doesn't start until midnight. Separate research points to another important restriction — a limit on the number of teenage passengers riding in vehicles driven by teenagers.
Most U.S. states and Canadian provinces have adopted some form of graduated licensing, but "only a handful have programs we rate as strong," Williams says. "If jurisdictions would upgrade their laws, as some have done, it's likely that graduated licensing would become even more effective."