THE HUMAN FACTOR IN ROAD SAFETY

Several studies based on accident analyses in depth have tried to establish the relative weight of vehicle, road and human factors as causes in road accidents. The results clearly point to the human factor as the main cause. But an analysis of the road traffic process and its development in a historical perspective indicates that the question and consequently also the answer are improper. It is normally not the failure of a component but the failure of a system interaction that causes accidents. However, the problem remains also with the systems approach - how to decrease the human errors in traffic. The common denominator of human mistakes seems to be lack of adequate information - from the road, the road environment, other road users and the vehicle. The information available in traffic is analysed both from the point of view of the road user and the road and traffic engineer. Possible ways to overcome informational deficiencies in the system are discussed on the basis of the three principal approaches - road user selection, road user improvement, adaptation/design of environment to road user characteristics. The conflict between the human engineering approach and the risk homeostasis hypothesis is analysed. Efforts are finally made to evaluate the possible effects of various improvements of road user selection: various ways to improve road user performance, such as education, training, enforcement; and various ways to adapt road design and delineation, road signs and signals, rules and laws, and vehicle dynamics to human characteristics and limitations (a). The number of the covering abstract of the conference is TRIS No. 368448. (TRRL)