The intention of this project was to examine the safety issues associated with two-up driving, the practice by which two drivers are carried in a truck or a coach and take turns to drive. An extensive review was undertaken of the sleep, shift-work and transport literature in a search for relevant research findings. Transport companies were visited and interviewed to obtain data on opinions and operational practice. Research on sleep and shift-work has consistently shown that working during periods in conflict with the body's natural rhythms can be harmful to health and cause a deterioration in vigilance and performance. Drivers working for long periods, especially at night, become fatigued, and crash rates rise with excessive hours behind the wheel. However, careful comparison of controlled groups has shown little or no difference between two-up and single drivers when confounding variables are accounted for, such as the extent of off-vehicle work and the time of day during which the driving is undertaken. The few studies which allow direct comparison of crash rates between two-up and single drivers have shown little significant difference between the two groups, with any differences that do exist favouring two-up operation. It is likely that there is a substantial degree of self-selection, coping, and adaptation among two-up drivers, who can therefore perform with no less safety than their colleagues driving alone. This may be at some physiological cost, and close monitoring will be required to minimise abuse of driving hours. (A)
Samenvatting