No abstract

to collisions of cars and lorries. Among 296 deaths of car occupants within 12 hours of injury, Ruffel Smith (1970) found that more than half were due to collisions with lorries. In our present series of 564 car occupant deaths 40% were from such collisions. It is difficult to apply appropriate weightings for different traffic conditions, but if 40% is a fair estimate it implies that in Great Britain car/lorry collisions cause about 1,000 deaths annually. This is as many as all the deaths due to accidents at work as studied by the recent Robens inquiry (Secretary of State for Employment, 1972).At first sight it is surprising that these collisions should be so common since lorries are outnumbered by cars by 7-1. The explanation seems to be an incompatability between the two types of vehicle. The lorry is heavy and strongly built to carry heavy loads. Rising gradients slow it down, falling gradients may cause it to go out of control. The car by contrast is light and built to maintain high speeds with light loads. Grime (1971) studied the theoretical mechanics of impacts between vehicles of different sizes. Of the lorries in our survey of which we know the weights, more than half were over 5 tons unladen. Most of the collisions, therefore, had a "mass-ratio" of at least 5. In Grime's analysis this implies a 95% or more risk of serious injury to car occupants with virtually no risk to the lorry occupants. This is consistent with our finding of 224 deaths of car occupants with five deaths of those in lorries.The unfavourable terms of this conflict has important implications for methods of protection. Whereas several studies show that seat belts will prevent 50% of injuries to car occupants, in our car/lorry collisions we estimate this could be only about 20%. The figure falls to about 10% for collisions of cars into the rear of lorries where so often the rear overhang or protruding load penetrates the windscreen area and so eliminates the protection normally afforded by the front of the car.Collisions into the rear of lorries are several times more frequent in dark than in light conditions in spite of there being less traffic of all kinds at night. This suggests there is room for improvement in making lorries more conspicuous. The current experiment with extra coloured markings may yield some benefit and there could well be other ways to warn motorists of impending danger. Elimination of the rear overhang of lorries and improved lighting might prevent some of the worst collisions but the underlying incompatibility of light and heavy vehicles remains. A more fundamental solution is the segregation of the two types of traffic on separate roads as on some highways in the United States. Another solution, perhaps more appropriate to this country, is to take account of the impending world shortage of oil supplies and save both fuel and human lives by using rail rather than road transport.We wish to thank Miss B. Roberts, for her help in this analysis, and the coroners and police of the areas studied, for their kind co-o...

No abstract

No abstract