Research article
Graduated Driver Licensing Decal Law: Effect on Young Probationary Drivers

https://doi.org/10.1016/j.amepre.2012.09.041Get rights and content

Background

Decal laws have been implemented internationally to facilitate police enforcement of graduated driver licensing (GDL) restrictions (e.g., passenger limit, nighttime curfew) but have not been evaluated. New Jersey implemented the first decal law in the U.S. on May 1, 2010.

Purpose

The aim of this study was to evaluate the effect of New Jersey's law on the rate of citations issued for violation of GDL restrictions and police-reported crashes among probationary drivers aged <21 years and to estimate the number of probationary drivers whose crashes were prevented by the law.

Methods

New Jersey's licensing and crash databases were linked from January 1, 2008 to May 31, 2011, and each driver's license status, age, and outcome status were ascertained for each month. Monthly rates were calculated as the proportion of probationary drivers who experienced the outcome in that month. The pre-law period was defined as January 2008–January 2010 and the post-law period as May 2010–May 2011. Negative binomial regression models with robust SEs were used to determine the law's effect on crash and citation rates (adjusted for gender, seasonal trends, and overall trends) and estimate prevented crashes. Analyses were conducted in 2012.

Results

In the first year post-law, there was a 14% increase in the GDL citation rate (adjusted rate ratio 1.14 [95% CI=1.05, 1.24]); a 9% reduction in the police-reported crash rate (adjusted rate ratio 0.91 [95% CI=0.86, 0.97]), and an estimated 1624 young probationary drivers for whom a crash was prevented.

Conclusions

Findings suggest that the law is positively affecting probationary drivers' safety. Results contribute to building the evidence base for the effectiveness of decal laws and provide valuable information to U.S. and international policymakers who are considering adding decal laws to enhance existing GDL laws.

Introduction

Motor vehicle crashes are the leading cause of death among U.S. adolescents, with men/boys accounting for over 70% of all deaths.1, 2 Graduated driver licensing (GDL) laws are a cornerstone of public policy aimed at reducing the burden of crashes on adolescent health. All U.S. states have GDL laws in place, designed to phase adolescents into licensure by delaying and/or extending the learning period and by introducing a “probationary” phase between the permit and the full-privilege (basic) driver license phases. During the probationary phase, young drivers are restricted from engaging in certain behaviors known to increase their crash and resultant fatality risk, including carrying passengers, driving at night, and using electronic devices.

Evaluations of GDL laws and specific GDL restrictions have consistently shown reductions in the prevalence of teen driver crashes.3, 4, 5, 6 However, the effectiveness of current laws has been limited by the inability of police officers to enforce them, given that identifying a probationary driver requires a traffic stop and visual inspection of the license.7, 8 Thus, the potential for GDL laws to have an even greater impact on reducing crashes in part hinges on efforts to enhance police enforcement of these restrictions.

To facilitate GDL enforcement efforts, several European and Asian countries, as well as jurisdictions in Australia and Canada, require novice teen drivers to display highly visible decals on their cars. The theory behind decal laws is that they enhance police enforcement, improve compliance with GDL restrictions, reduce risky driving among probationary drivers, and ultimately reduce the prevalence of young driver crashes.9 However, previously implemented decal laws have not been rigorously evaluated. New Jersey recently implemented the first-in-the-nation GDL decal law (Kyleigh's Law), requiring permitted and probationary drivers aged <21 years to display small decals on their license plates, regardless of when their license was issued (i.e., even if they initially obtained their license prior to implementation of the law). This implementation provides a unique opportunity to conduct an evaluation of this novel intervention.

The primary objective of this study was to examine the effect of New Jersey's decal law on the monthly rate of: (1) citations issued to probationary drivers for violation of a GDL restriction; and (2) police-reported crashes among New Jersey probationary teen drivers during the first year following the law's implementation. Secondary crash outcome measures included injury, nighttime, single-vehicle, multiple-vehicle, and peer-passenger crashes. Finally, a goal of the current study was to estimate the number of probationary drivers for whom a crash was prevented by the decal law.

Section snippets

Data Sources

The New Jersey Motor Vehicle Commission's Licensing and Registration Database contains information on all New Jersey drivers' progression through the licensing process, as well as the type and date of driver “events” (e.g., moving violations, citations, crashes). Identifiable data were obtained for all individuals who had a license at some point from January 1, 2008 through May 31, 2011 (n=6,714,288 drivers). These data were linked to New Jersey Crash Record data over the same time period (n

Number of Probationary and Licensed Drivers

The number of probationary drivers aged 17 years remained stable at approximately 65,000 throughout the study period (Figure 1). The median number of new probationary licenses issued per month was also similar before and after the law became effective (pre-law: 8718/month; post-law: 8418/month), as was the median age of the driver (17.1 years for both) at the start of the probationary license period. The number of probationary drivers aged 18–20 years who were not yet eligible to obtain a basic

Discussion

By making probationary drivers easily identifiable to police, decal laws have been theorized to both enhance enforcement of GDL restrictions and increase the likelihood that drivers comply with GDL restrictions, thereby reducing their crash risk. Although decals have existed for more than a decade in other countries, there is very little previous evidence to support this theory.9 This study adds valuable initial evidence for the impact of a decal law on enforcement of GDL provisions by police,

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  • Young Driver Compliance With Graduated Driver Licensing Restrictions Before and After Implementation of a Decal Provision

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    Our previous evaluation of NJ's decal provision found that overall crash rates among young intermediate drivers decreased 9.5% in the 2 years after implementation [10,13]. Police enforcement—measured by per-driver rates of citations that were issued for violating GDL provisions—also increased but was primarily limited to the first year after the provision [10,13]. Although improved compliance with GDL provisions is one of the primary mechanisms by which decal provisions are hypothesized to lead to crash reduction (see Figure 1) [8], the findings of this study suggest that the association between NJ's decal provision and reduction in crashes was not mediated by an increase in intermediate drivers' compliance with nighttime and passenger restrictions.

  • Graduated driver licensing (GDL) in the United States in 2016: A literature review and commentary

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    For example, in a 2014 survey, only 22% of teenagers who were subject to it approved of the policy (Williams & McCartt, 2014). However, evaluations have indicated that the decals law has had both short-term and longer-term crash reduction effects for intermediate license holders (Curry, Elliott, Pfeiffer, Kim, & Durbin, 2015; Curry, Pfeiffer, Localio, & Durbin, 2013), but no such effects for learners (Curry et al., 2015). A recent study indicated that compliance with night and passenger restrictions in New Jersey did not improve after the law went into force, but compliance was already high (98% for the nighttime restriction, 91% for the passenger restriction; personal communication, A.E. Curry).

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Melissa Pfeiffer was unaffiliated with an institution at the time this research was completed.

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