This paper presents some empirical studies of conditions under which road user behaviour may change so as to reduce the impact of safety measures. Experimental field studies of truck drivers have shown a risk-compensation effect under a range of conditions. The author has been examining the problem in a more controlled way, by exploring subjects' choices in a computer simulation of basic elements of the driving task. Simulation enables the variation of the level of uncertainty in the sequence of potentially aversive events or hazards, experienced on a simulated journey, and of the utility of gambling on those events not occurring. The simulation took the form of a game, on each play of which a subject 'travelled' on a 'journey' with 15 potential hazards. Preliminary results suggest that safe behaviour may be modified by changing risk probability and the reward value of alternative responses. The important safety questions were found to be the conditions under which: (1) risk compensation to reduce risk is inadequate and fails; and (2) risk compensation to increase risk is adequate and successful. Initial results show that subjects' performance seems to be based on neither risk homeostasis nor utility maximisation. For the covering abstract see IRRD 870346.
Samenvatting