Controlled study of ISA effects : comparing speed attitudes between young volunteers and external controls, and the effect of different ISA treatments on the speeding of volunteers.

This study is a part of an ongoing ISA project in Denmark. Its aim was to clarify two human factors issues, (1) the difference in attitude between ISA-volunteers and non-volunteers, and (2) the relative impact on speeding of two factors, ISA-information and driver motivation. The first part of the study compared survey data from ISA-volunteers with those of non-volunteers. The two groups differed in their judgement of ISA features and anticipated effects of driving with ISA, whereas no differences were found in judgement of speed limits, attitude to speeding or reported driving style. The second part of the study was a driving experiment in which two factors, informative ISA and an economic incentive for not speeding, were manipulated between groups of volunteers. A control group had ISA switched off and received insurance discount independent of their speeding. This group did not reduce their speeding in the experiment period, whereas another group, also with ISA switched off but with insurance discount dependent on their speeding reduced their speeding by a small amount. Two groups, both driving with ISA switched on showed a substantial reduction in their speeding. The effect of informative ISA alone was substantial, which presumably prevented a further gain from combining ISA information with the incentive. (Author/publisher)