Understanding intentions to override intelligent speed assistance prior to widespread availability: An application of the theory of planned behaviour.

Intelligent Speed Assistance (ISA) offers a technological solution to reduce speeding that will become more common in vehicles in the short to medium term. Many implementations allow drivers to override the system's speed control and minimising such interventions can optimise safety benefits. This paper aims to inform behaviour change interventions to reduce ISA overriding targeted to drivers as they obtain vehicles fitted with ISA. We explore the beliefs underlying intentions to override ISA to exceed the speed limit in drivers with limited ISA experience using the Theory of Planned Behaviour. In a sample of 121 drivers (mean age 36 years), regression modelling showed that attitudes strongly predicted intentions with an additional contribution from subjective norms but not perceived behavioural control. Behavioural beliefs underlying attitudes addressed overriding ISA for (1) responsibly controlling the car to minimise crash risk and (2) reducing journey times and enjoying fast driving. Salient normative beliefs focussed on groups that would disapprove of overriding ISA including emergency services and parents. We discuss how these beliefs might be addressed in interventions to maximise the safe adoption of ISA.