1.2 GDL Learner’s Permit Length, Supervised Hours
With a learner’s permit, a novice can drive when accompanied by an adult supervisor. The learner’s permit allows and encourages beginning drivers to acquire substantial driving experience. To aid this, most States require the learner’s permit to be held for a minimum period of time, and most require a minimum number of supervised driving hours. Surveys show that parents and teenagers strongly support the learner’s permit holding period and supervised driving requirements (Block & Walker, 2008; Mayhew, 2003; McKay et al., 2008; Williams, 2011; Williams et al., 2011).
Use: As of September 2019 there were 48 States and the District of Columbia that required learner’s permits to be held for at least 6 months, with 8 of these States requiring a minimum holding period of a full year. However, Connecticut and South Dakota reduce the required length of time for a permit to be held if the young driver completes driver’s education (IIHS, 2019b).
Forty-six States and the District of Columbia required some minimum number of supervised driving hours, with about half of them requiring 50 hours. Forty-one States plus the District of Columbia required that at least some of these hours be obtained at night. In addition, a few States required additional supervised hours to be completed during the intermediate license phase (GHSA, 2019a). Some States reduced or eliminated supervised driving requirements for driver education graduates. However, evidence suggests this practice results in higher crash rates among young drivers (Mayhew, 2007).
Effectiveness: Since learner’s permit drivers are being supervised, it is not surprising that crash rates during the learner’s permit period are very low. For young drivers holding their first unsupervised licenses, the limited available evidence suggests that crash rates decreased after jurisdictions with no learner’s permit holding requirement implemented a 6-month requirement (Ehsani et al., 2013; Mayhew, 2003). Moreover, longer permit holding periods appear to result in even larger crash reductions. Masten et al. (2013) found that a 9- to 12-month leaner’s permit holding period resulted in 26% lower fatal crash incidence among 16-year-old drivers and 17% lower incidence among 17-year-olds compared to requiring learner permits for up to 4 months. Furthermore, Curry et al. (2014) found that intermediate-phase drivers had incrementally smaller increases in crash rates during their initial months of driving independently for every month up to 6 months that they delayed obtaining full licensure.
However, the effect of supervised hours is currently unclear. Some studies have found supervised hours requirements lead to reductions in fatal crashes when hourly requirements are combined with mandatory learner’s permit holding periods (Baker et al., 2006; Lyon et al., 2012). However, evaluations have found no relationship between the number of required supervised driving hours and fatal crash involvement among young drivers (Ehsani et al., 2013; Foss et al., 2012; Masten et al., 2013; McCartt et al., 2010). Based on telephone interviews with parents in 5 States, only 32% knew the correct number of supervised driving hours their teens were required to complete (Foss et al., 2012; O’Brien et al., 2013). Therefore, the lack of effect of supervised hours on fatal crash outcomes may be explained, in part, by a lack of parental knowledge of the supervised driving requirements.
Costs: Once GDL is in place, requirements for the learner’s permit can be implemented at very little cost.
Time to implement: GDL requirement changes typically require about 6 months to notify the public and implement the changes.