Increasing drivers’ intentions to use intelligent speed assistance: a randomised controlled trial of a theory of planned behaviour-based intervention

Technological advances can provide an opportunity to reduce road traffic crashes.Intelligent Speed Assistance (ISA) is one technology that is increasingly available in modern vehicles. The full realisation of ISA's safety potential is contingent upon the extent to which drivers choose to drive with the system turned on. Based on the theory of planned behaviour, we designed a brief online intervention (comprising a leaflet and animation) to strengthen intention to use ISA that could be presented to drivers when purchasing an ISA enabled vehicle. A randomised controlled trial with a sample of 1029 participants showed that the intervention had a small-to-medium sized effect in strengthening intention to use ISA in drivers who do not have ISA installed in the vehicle they usually drive compared to those in an active control condition. This effect remained significant one week and one month after the intervention. Further analysis revealed that the effect of the intervention was partially mediated by attitudes toward ISA use, underpinned by changes in in behavioural beliefs about the advantages and disadvantages of turning ISA on. The results support the use of our freely available intervention to encourage drivers to voluntarily turn ISA on when purchasing an ISAenabled vehicle.