Crash Risk and Risky Driving Behavior Among Adolescents During Learner and Independent Driving Periods.

PURPOSE: Novice adolescents' crash rates are highly elevated early in licensure, despite substantial practicedriving during the learner period. The objectives of this study were to examine the variability in measures of driving risk among adolescents during the learner and early independent driving periods and evaluate how risk varies by driving experience, gender, time of day, and road surface conditions.

METHODS: Objective driving data were collected in a naturalistic cohort study of 90 adolescent drivers with learner driving permit and 131 experienced adult drivers. Participants' private vehicles were equipped with data acquisition system documenting driving kinematics, miles driven, and video recordings of the driver and the driving environment. Crash/near-crash (CNC) and kinematic risky driving (KRD) rates were calculated during the learner and early independent driving periods by gender (female/male), time of day (day/night), and road surface conditions (wet/dry) for adolescents and adults.

RESULTS: CNC and KRD rates of adolescents were similar to adult drivers during the learner period (CNC: incident rate ratio [IRR] = 1.67, confidence interval [CI] = .98-2.82 and KRD: IRR = 1.04, CI = .78-1.40, respectively), but dramatically higher in the first year of independent driving (CNC: IRR = 6.51, CI = 4.03-10.51 and KRD: IRR = 3.95, CI = 2.96-5.26, respectively), and particularly elevated the first 3months of licensure. Adolescent KRD rates were higher for males than females and invariably higher than adult rates during day and night, wet and dry conditions.

CONCLUSIONS: While the learner driving period was relatively safe for adolescents, the transition to independent driving was typified by a dramatic increase in risk among adolescents that was higher than adult rates overall and under varying driving conditions.