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Effectiveness: Effectiveness demonstrated for nighttime restrictions 5 Star Effectiveness demonstrated for nighttime restrictions Cost: $
Use: High
Time: Medium

Teens are less experienced at the task of driving, so driving requires more of their deliberate attention than is the case for experienced drivers (Lansdown, 2002). Some studies suggest that drivers 16 to 24 are somewhat more likely than other age groups to drive while drowsy (Royal, 2003; Wheaton et al., 2014).

The nighttime driving restriction of GDL reduces the likelihood of drowsiness for newly licensed drivers. Driving at night is associated with higher fatal crash risk than during the day for teen drivers (McCartt & Teoh, 2015), and also may pose greater risks of drowsy driving. The NCHRP guide for reducing crashes involving young drivers describes the key provisions of GDL laws (Goodwin et al., 2007). The Insurance Institute for Highway Safety (IIHS, 2019) and the Governors Highway Safety Association (2019) summarize State GDL laws. These summaries are updated monthly. See the Young Drivers chapter, Sections 1.1 and Appendix A6, Section 1.7, for a complete discussion of GDL for beginning young drivers.

Use: As of November 2016, all 50 States and the District of Columbia had some GDL components in place. The laws in 49 States and the District of Columbia do not allow driving during certain nighttime hours during the intermediate license stage. (This stage limits unsupervised driving during high risk situations.)

Effectiveness: Several studies document that nighttime GDL restrictions reduce teenage driver crashes and injuries (Hedlund & Compton, 2005; Goodwin et al., 2007; Williams, 2007; Williams, 2017). Young drivers are involved in a disproportionately high number fatal crashes that occur between 9 p.m. and 6 a.m. compared to the number of miles driven during that time frame (Williams & Preusser, 1997). When a GDL system with appropriate restrictions (including earlier nighttime restrictions) is implemented, crash rates for 16-year-old drivers are reduced 25 to 35% and for 17-year-old drivers by 15 to 20% (Goodwin et al., 2007). In North Carolina following the introduction of a 9 p.m. nighttime restriction, Foss et al. (2001) reported a 43% decrease in crashes between 9 p.m. and 5 a.m. compared to a 20% reduction in daytime crashes. After a nighttime restriction beginning at midnight was implemented in Michigan, there was a 53% decrease in crashes among 16-year-old drivers between midnight and 4:59 a.m. compared to a 24% decrease during the day (5 a.m. to 8:59 p.m.) and a 21% decrease from 9 p.m. to 11:59 p.m. (Shope et al., 2001). Goodwin et al. (2007) recommend nighttime GDL restrictions start earlier (i.e., 9 p.m.) rather than later.

One factor that may undermine the effectiveness of GDL restrictions in teen drivers is the perception that the risk of penalty from not complying with the law is low. In particular, a study of GDL violations in Washington State and North Carolina found low overall enforcement of the GDL requirement laws (AAAFTS, 2014). The AAA Foundation also found that a high proportion of GDL citations, including those requiring nighttime supervision (27%), were dismissed by the courts, which “may very well be detrimental to the overall effectiveness of GDL programs.”

Costs: Publicity for GDL restriction changes can be delivered directly by the Department of Motor Vehicles to young drivers as they apply for their learner’s permits and provisional licenses, so costs can be minimal. Information about GDL restrictions can also be provided through driver education courses.

Time to implement: GDL nighttime restriction changes require several months to implement for drivers receiving a provisional license. They then will take 1 or 2 years before all provisionally licensed drivers are subject to the new restrictions.