Road crashes are random events. While the number of crashes during a certain time period such as a month or a year indicates the level of risk on the road, it may fluctuate without any change in the actual underlying risk. If the number of crashes increases or decreases, it indicates one of two possibilities: (1) the risk has changed, (2) the difference is due to the stochastic nature of the event - that is, it is due to a random fluctuation. A control chart system is developed in the paper to identify the occurrence of actual risk changes. The paper discusses the development of control charts to monitor fatalities at the national level and the potential for applying the method to fatal and serious injuries at a district level. Safety programmes are developed to reduce the risk to a target level. Drawing a trend line from the current road toll level to an appropriate value, the control chart method discussed in the paper will indicate the likelihood of the target being achieved. (A)
Abstract