In order to achieve rational road maintenance, each road maintenance authority has to draw up an integral maintenance program. Such a program consists of a policy-guide, an inventarisation of the actual situation, a vision on the future situation and a program of measures for a period of five years. Letting aside asphalting of roads, constructions, landscaping and environment, traffic facilities are also included in the maintenance program. Road restraint systems such as guardrails, safety barriers and crash cushions are also part of traffic facilities. The road maintenance authority has to gain a clear insight into roadside hazards. Hazards which show a favourable relation between safety measures and costs have priority to be dealt with. An aid to this is the manual `Prioberm', drawn up by DHV Environment and Infrastructure by order of an in co-operation with the Dutch Department of Public Works. Prioberm contains: - a global inventarisation of relevant road and traffic characteristics when situations are not consistent with the guidelines; and - establishing priorities on the base of cost-benefit analysis. The reasons and the seriousness of roadside accident in a certain situation of a freeway can be subdivides into three parts: 1. the probability the driver leaves the road; 2. the probability the driver collides with an obstacle or other road users; and 3. the probability of injury or fatality. The relations between these three probabilities are modelled in Prioberm. Prioberm does not predict the number of accidents, but calculates the relative unsafety of the road sides. The method is a practical tool incorporating the available knowledge about road side hazards. (A)
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