Predicting drivers’ intentions to voluntarily use intelligent speed assistance systems: an application of the theory of planned behaviour

Intelligent Speed Assistance (ISA) could substantially decrease road traffic crashes and is becoming more common in vehicles in high income countries. Increasing ISA adoption and usage is key to realising the potential safety benefits. Therefore, identifying the predictors of intentions to use ISA is important to understanding how to encourage its use via road safety education during roll out. The current study used the Theory of Planned Behaviour (TPB) to predict intentions to (i) turn ISA on and (ii) override ISA when turned on among 554 drivers who reported not having ISA currently installed in their vehicle. The TPB explained 76% and 59% of the variance in turning on and overriding intentions respectively. Attitudes were key predictors of both ISA behaviour intentions. Subjective norms predicted intentions to turn on but not override ISA while perceived behavioural control did not independently predict intentions towards either behaviour. Important beliefs included that ISA could reduce the risk of crashes and speeding penalties and fines, and that driving with ISA makes driving more relaxing. The beliefs identified can be targeted in interventions aiming to increase ISA usage and adherence.