Major differences in basic accident avoidance characteristics are almost inevitable when one compares typical private cars with various other cases of motor-driven road vehicles-and they are becoming more marked. The search for ever lower air resistance has resulted in low profile cars with fairly large areas of curved and steeply sloping glass, front and rear. When encountering low lying or drifting banks of fog or even early morning mist, the truck driver, generally sitting above such low banks of translucent fog, will be able to see reasonably clearly the general layout of the road ahead, as well as the shapes of tallish vehicles in front and to the side. He may, however, fail to notice the car in front and ride over it, crunching it in the process, for its driver, unable to see where he is and whether there are other vehicles ahead of him, will tend to put on his brakes-and they will be fast acting.

Braking performance of trucks is not as good as that of cars even when the respective systems are working perfectly.

The very real benefits to commercial vehicles which could be provided by anti-lock braking, in terms of better braking under adverse conditions and, above all, improved vehicle stability and directional control during emergency braking, have been well understood, but relatively few have been gitted to commercial vehicles, whereas it will not be long before some form of anti-lock braking will become available on high priced cars as well as modestly priced mass produced small cars. This will soon create an etrtirely new situation, in which the car driver can stop his vehicle in a controlled and safe manner, no matter what the weather, road or traffic conditions are or how rashly or inexpertly thc driver reacts to them, whereas very few truck drivers will have the benefit of such technological quick-reacting devices.

For the wide range of possible surface textures, the tyre-to-road grip of bus and truck tyres will be around 2/3 or 3/4 that provided by car tyres intended for Western Europe. The minimum braking distance will, therefore, be 15% to 22% longer. In the foreseeable future there is little change of this basic performance gap being closed.