Prolonged Heavy Vehicle Driving Performance: Effects of Unpredictable Shift Onset and Duration and Convoy versus Independent Driving Conditions

摘要

Truck driver safety was studied under conditions of prolonged normal driving, prolonged continuous convoy during, and continuous convoy during under conditions of task uncertainity. In all experiments drivers were required to drive an experimental truck for four consecutive days. Dependent variables were driver performance, self ratings, and endocrine changes. Apart from changes over time, where possible the effects of age and time of work period onset were determined. Symptoms of fatigue were most typical of the end of the driving shift, becoming evident from about the 9th hour of driving, and were particularly characteristic of older drivers on a shift finishing at 02.30 hours. Nevertheless the requirement to drive 11 hours per day for 4 consecutive days did not lead to conspicuous deterioration in driving performance under normal driving conditions. Even under continuous convoy driving such prolonged work did not produce impairment but elicited compensatory adjustments toward the end of the late shift. Finally, task uncertainity was not found to induce earlier fatigue. Drivers appeared to adjust to this condition by covertly anticipating a demand in excess of actual requirement. A behavioural analysis of the driving task was proposed and among other features its implications for driver fatigue and traffic accidents were discussed.