Risk can serve as the basis for the selection of research and action themes which should then be justified on the basis of cost-benefit considerations. Decision-making can be carried out on the basis of comparative risk levels, on the basis of accident and injury data (without risk) and according to costbenefit considerations. Each method has advantages and disadvantages and should be selected according to the circumstances. Decision-making on the basis of the numbers of accidents, injuries or fatalies focuses on the size of the problem and prevents us from focusing our efforts on a segment of
road safety that might look bad from the point-of-view of risk but which might not be very significant in terms of the quantities involved. Decisionmaking on the basis of risk tends to lead to actions that are considered fair in terms of the road users involved. If a segment of road, or a certain type of road, or a group of road users has a risk that is higher than the risk for another group or higher than average, this is considered unfair and decision-makers are urged to adopt policies that would lead to an absolute and relative decrease in risk for that group. In practise, such decisions are
not reasonable, not possible and almost certainly not economical. Motorcycle riders have higher risks than car occupants, pedestrians have higher risks of dying from an injury than car occupants, regional and local roads have higher levels of risk than motor-ways and so on. The final decision should generally be based on cost-effectiveness considerations because, in the field of road safety, like in any other field, the amount of expenditure is limited and investments should be allocated to those fields that produce the highest accident, casualty and fatality reduction that can be achieved per
unit of money invested.