Modelling acceptability of the intelligent speed adapter

The Intelligent Speed Adapter (ISA) is an example of in-car telematics equipment that is developed to reduce speeding. It can be introduced as a policy instrument to improve speed limit compliance and with that traffic safety. However, previous research indicated that acceptability of this type of instruments is rather limited. Adopting a policy that may increase acceptability before introduction of the instrument is therefore recommended. To formulate such a policy, understanding the factors that influence ISA acceptability is required. To that effect, a causal model that disentangles the direct and indirect effects of predictor variables on ISA acceptability is developed and estimated. The model includes car drivers’ attitudes, opinions and beliefs on the speeding problem, the policy goal and the policy instrument ISA, as well as speed related behaviour and socio-demographic variables. This paper presents the direct and total effects of these variables on ISA acceptability. The results suggest that explaining clearly how ISA can contribute to attaining various personal and societal goals may be a viable policy to increase ISA acceptability.