Variability in crash and near-crash risk among novice teenage drivers

Using video monitoring technologies, the authors investigated teenage driving risk variation during the first 18 months of independent driving. Driving data were collected on 42 teenagers whose vehicles were instrumented with sophisticated video and data recording devices. Surveys on demographic and personality characteristics were administered at baseline. Drivers were classified into three risk groups using a K-mean clustering method based on crash and near-crash (CNC) rate. The change in CNC rates over time was evaluated by mixed-effect Poisson models.
Results of the study showed that - compared with the first three months after licensure (first quarter) - the CNC rate for participants during the third, fourth and fifth quarters decreased significantly to 59%, 62%, and 48%, respectively. Three distinct risk groups were identified with CNC rates of 21.8 (high-risk), 8.3 (moderate-risk), and 2.1 (low-risk) per 10000 kilometers traveled. High- and low-risk drivers showed no significant change in CNC rates throughout the 18-month study period. CNC rates for moderate-risk drivers decreased substantially from 8.8 per 10000 kilometers in the first quarter to 0.8 and 3.2 in the fourth and fifth quarters, respectively. The three groups were not distinguishable with respect to personality characteristics.
The study concludes that teenage CNC rates varied substantially, with distinct high-, moderate-, and lowrisk groups. Risk declined over time only in the moderate-risk group. The high-risk drivers appeared to be insensitive to experience, with CNC rates consistently high throughout the 18-
month study period, and the moderate-risk group appeared to learn from experience.