Guard rails

A French study [4] was concerned with collisions with guard rails. In 1993-1995 there were 63 fatal collisions of motorcyclists with a guard rail in France per year. This is 8% of all motorcycle fatalities. Records of injury accidents were used to reconstruct the accidents, which was only possible with 157 out of 239 records:

In 21 cases the motorcycle hit the rail but the rail had nothing to do with the injuries of the rider
In 43 cases the motorcycle hit the rail and the rider was thrown away and injured (42 of them without hitting the rail)
In 50 cases the motorcycle and rider hit the rail (in 29 cases with the rail post)
In 43 cases the rider fell and slid under the rail

The number of such cases is dependant on both the frequency of motorcycles leaving the road by accident and the presence of guard rails at such places. What would be the outcome of these accidents if the guard rail had not been there is difficult to decide since the guard rail was there to prevent collisions with other objects. On the basis of the records Brailly suggests that in about half these cases the injuries would have been less severe with a different design of the rail.