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Forgiving road

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About one fifth of all traffic accidents in Belgium are collisions with obstacles off the carriageway. Generally a single vehicle is involved in these.

However, there is a considerable difference in severity of the consequences of such accidents. The risk of death after a collision with an obstacle off the carriageway is at least twice as high as the average risk of being killed in a traffic accident. And the risk of serious injuries is still at least 60 % higher than on average.

The consequences of a collision of a passenger car with an obstacle off the carriageway are, therefore, much more serious. To prevent such accidents, the full range of available measures can and must be used. However, it is doubtful whether all these awareness or even penalizing actions can exclude all accidents. Even the most careful driver is liable to be overcome by fatigue or to make a driving error at some time.

The “forgiving road” approach aims not only to prevent accidents, but also to lay out the road in an intelligent way such that (unintentional) driving errors are not immediately punished by serious injuries or worse.

Ideally there should be no obstacles along the road. When this is not feasible, it can be investigated how to place or re-place them so as to minimize the risk of collision. Another option is to use so-called breakaway or collapsible obstacles. Only when removal, re-placing or the breakaway alternative are not feasible, suitable restraint systems can be considered. In such cases the remedy must not be worse than the evil, i.e., the restraint system must not form a dangerous obstacle by itself.

There is no standard recipe for laying out forgiving roads. When (re)developing a road, it is always advisable to make sure that the choices made will not have any adverse consequences, even in the long term, for (unintentionally) errant vehicles. Measures to make a road more “forgiving” are generally relatively simple and immediately effective.

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