Since 1988 Danish rules prescribe all lorries above 6,000 kilos to carry a close proximity and a wide-angle mirror besides the ordinary rear-view mirror on the right side of the vehicle in order to reduce the number of accidents involving right-turning lorries and two-wheelers. The safety effect of the extra mirrors has been investigated in a before-and-after study including a control group assessed to be unaffected by the extra mirrors. Based on this control group, no significant safety effect on the extra mirrors can be demonstrated, if fatal and personal injury accidents are considered as a whole. However, fatalities alone have decreased in comparison with the control group. It cannot be excluded that this decrease may be due to some effect of the extra mirrors, but if so, the safety effect has turned out to be more modest than anticipated. The lack of effect may to a great extent be attributed to the large number of poorly adjusted mirrors. Evaluation results of a campaign conducted in 1992 showed that less than half of the investigated lorries had correctly adjusted mirrors. (A)
Abstract