Kinematic risky driving behavior among younger and older drivers: Differences over time by age group and sex

Objective: This research examined the incidence rates of elevated gravitational force events (kinematic risky driving, KRD) among 16- to 17-year-old drivers compared to those of 18- to 20-year-old, 21- to 25-year-old, and 35- to 55-year-old drivers over a 12-month period. Methods: Data were sampled from the Strategic Highway Research Program 2 (SHRP2) naturalistic driving study that recruited a U.S. national sample of study participants. General linear mixed models (GLIMMIX) for recurrent events were used to estimate KRD incident rates for age cohorts in 3-month periods. Results: KRD incidence rates for 16- to 17-year-old drivers were higher than the rates for older drivers at each 3-month period. Analyses of individual differences for the 12-month period indicated that incidence rates for the 16- to 17-year-old group were 1.84 times higher than the rates for 18- to 20-year-old drivers, 2.86 higher than those for 21- to 25-year-old drivers, and 4.92 times higher than those for 35- to 55-year-old drivers. The incident rate for 16- to 17-year-old males was 1.9 times higher than that for same-aged females in the first 3 months and 2.3 times higher over 12 months. Over the study period, KRD rates of 16- to 17-year-old participants declined 24.5% among females and 18.0% among males. Conclusions: KRD rates were higher among younger relative to older, more experienced drivers and did not decline over time, consistent with a protracted period of risky driving behavior. The persistently higher KRD rate among young drivers suggests the need to enhance crash prevention approaches, such as feedback about abrupt maneuvering, to young drivers and their parents.