This report explores the theoretical possibilities of defining exposure and risk, discusses the problems associated with the use of exposure and risk, and gives examples of various safety studies in which use is made of exposure and risk indicators. The report sets out with a definition of the three central terms used: accidents, exposure and risk. The conclusion reached is that there are general definitions of exposure and of risk, as used in the field of health prevention and risk analysis, but that in road safety practice, these terms should be defined within the context of the issue studied. In the case of transport, the most widely used measure of exposure is the number of kilometres travelled for each travel mode. In some cases, useful additional insight is provided by taking into account the speed of travel, in which case exposure is expressed as the amount of time spent in the traffic system. One of the developments in recent years has been the installation of electronic and telecommunication equipment inside vehicles and along roads. The increasingly widespread use of mobile phones also presents many new possibilities. As a result, it is becoming easier to collect up-to-date and reliable information on a variety of parameters that could be of importance in the calculation of vehicle exposure and risk. One of the contexts in which the term risk is used, is in comparing risks between different parts of the transport system, different transport modes or even different activities outside the field of transport.
Samenvatting