EFFECTS OF DISTRACTION AND DROWSINESS ON SIMULATED DRIVING PERFORMANCE IN POLICE OFFICERS
James, Stephen M.
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Motor vehicle collisions are a leading cause of police officer on-duty deaths. Distracted driving is a major contributing factor in motor vehicle collisions among the general public. Within policing, fatigue associated with shift work is a well-established and pervasive problem that affects officer performance, safety, and health. Although drowsy driving among post-shift workers is a well-established risk factor, no data are available about officer injuries and deaths due to drowsy driving. To address this gap in the literature, we assessed the impact of distraction, fatigue, and the interaction of distraction and fatigue on officers’ driving using laboratory experiments with high fidelity simulation. In addition, we assessed the ability of a well-validated psychomotor vigilance test to assess post-shift drowsy driving risks. Experienced police patrol officers (n=80) from all four shifts of a medium-sized city's police department were tested using a within- and between-subjects design to assess the impact of distraction and fatigue on individual officers, as well as the impact of different work shifts, on driving performance. Controlled laboratory experiments were conducted during which participants drove high-fidelity driving training simulators on two separate occasions: immediately following five consecutive 10:40-hour patrol shifts (fatigued condition) and again 72 hours after completing the last shift in a work cycle (rested condition).Generalized linear mixed effects model analyses of driving performance showed that officers’ distracted driving performance had significantly greater lane deviation (f=88.58, df=1, 308, p<0.001)—a leading indicator of collisions. This analytical framework found officers working night shifts had significantly greater lane deviation during post-shift, non-operational driving than those working day shifts (f=4.40, df=1, 150, p=0.038). The same method also showed that easy-to-measure psychomotor vigilance test (PVT) scores for reaction time predicted both lane deviation (f=31.48, df=1, 151, p<0.001) and collisions (f=14.10, df=1,151, p<0.001) during the simulated drives. We also found a significant impact of distraction (f=14.90, df=1, 305, p<0.001), working the graves (midnight) shift (f=4.89, df=1, 305, p=0.028), and distraction/shift interaction (f=4.81, df=1, 305, p=0.029) on the probability of a collision.This is the first experimental research to assess the impact of distraction, fatigue, and shiftwork on police patrol driving and post-shift driving.