The objective of this study is to see whether individual driver estimations of fatigue and the related conditions are accurate, what methodology drivers use when estimating the fatigue they experience and at which point they stop driving. This paper describes measurement of work load in professional drivers during winter and summer in1987, including fatigue experienced in the course of driving. Additionally, drivers were asked to estimate individually the level of fatigue they experienced during driving giving an hourly record of the symptoms they felt. The rating on the scale was from one to seven. The measurement was carried out in the course of one journey, i.e. driving from the point of departure to destination. Driving performance and working capacity decreased with the increase of fatigue. Drivers were observed to feel a little better after each break, but this improved condition was not long lasting. They grew more and more tired and the performance became more and more impaired. Studies of fatigue related conditions and driving performance have disclosed that drivers generally make only occasional breaks which are not long enough to provide proper rest.
Abstract