Highlights • Empirically testing road safety interventions, such as pay-as-you-drive are challenging due to external effects. • Evaluates changes in driver behaviour using a common measure of risk and controlling for the impact of the road environment. • Intervention incorporated both a financial reward and personalised information on participants’ speeding behaviour. • Results show that making drivers aware of their speeding behaviour is effective in changing behaviour. • Largest reductions in risk when drivers are shown their speeding behaviour and a financial incentive to reduce speeding.

Abstract New road safety strategies continue to be devised by researchers and policy makers with pay-as-you-drive (PAYD) schemes gaining increasing attention. However, empirically measuring the effectiveness of these strategies is challenging due to the influence of the road environment and other factors external to the driver. The analysis presented here applies Temporal and Spatial Identifiers to control for the road environment and Driver Behaviour Profiles to provide a common measure of driving behaviour based on the risk of a casualty crash for assessing the effectiveness of a PAYD scheme on reducing driving risks. The results show that in many cases personalised feedback alone is sufficient to induce significant changes, but the largest reductions in risk are observed when drivers are also awarded a financial incentive to change behaviour. Importantly, the more frequent the exposure to the speeding information, the greater the magnitude of the change. However, the changes are disproportionately associated with those that were already safer drivers in the baseline period suggesting that some drivers may be predisposed to changing their behaviour. These results suggest that it would be beneficial to provide real-time or daily feedback on speeding behaviour in conjunction with a financial reward scheme, potentially as a component of insurance premiums.