The expression 'behavioural adaptation'(BA), when used in the context of transportation psychology, describes the behaviour that occurs following a change to the road traffic system that was not intended by the initiators of that change. The impact of this behaviour on road safety can be positive, negative, or neutral; however, it is the negative, or safety reducing, effects of BA that are of primary concern to road safety professionals. Several theories have been advanced to explain how and why BA arises. For example, risk homeostasis theory proposes that a control mechanism maintains overall risk per unit time constant and, as a consequence, the number of collisions per unit time of driving remains fixed, independent of changes in the road safety system. Other theories have included causal factors other than risk compensation in their models. At the present time, no quantitative models of behavioural adaptation exist. One element that determines the degree to which humans rely on automation is the amount of trust they feel towards it, which in turn depends on a system's perceived competency. It is possible, therefore, that in-vehicle systems that are perceived by users to be 'trustworthy' are also those that generate more significant instances of BA. A study design that assesses the ability of lane departure warning (LDW) systems to induce BA is presented. Intended to alert a driver when their vehicle begins to drift outside lane boundaries, these systems are presently being hailed as having only positive effects on road safety, namely by reducing the number of run-off-the-road accidents. However, a complete understanding of their effects on driver behaviour has yet to be determined. For the covering abstract see ITRD E113725 (C 22328 CD-ROM).
Abstract