Novice drivers’ individual trajectories of driver behaviour over the first three years of driving

Key findings
• Identifying driver behaviour changes in new drivers can help reduce road crash risk.
• Violations, errors and slips increased linearly over the first three years of driving.
• Two to three classes of aberrant driver behaviour trajectories were identified.
• Classes of aberrant driver behaviour were mainly defined by initial levels.
• Men and young drivers were more likely to follow a trajectory of high aberrant behaviour.

Summary
Identifying the changes in driving behaviour that underlie the decrease in crash risk over the first few months of driving is key to efforts to reduce injury and fatality risk in novice drivers.

This study represented a secondary data analysis of 1,148 drivers who participated in the UK Cohort II study. The driver behaviour questionnaire was completed at six months and one, two and three years after licensure.

Linear latent growth models indicated significant increases across development in all four dimensions of aberrant driving behaviour under scrutiny: aggressive violations, ordinary violations, errors and slips. Initial levels of aberrant driver behaviour were important in identifying sub-groups of drivers. All classes showed positive slopes; there was no evidence of a group of drivers whose aberrant behaviour decreased over time that might explain the decrease in crash involvement observed over this period. Male gender and younger age predicted membership of trajectories with higher levels of aberrant behaviour.

These findings highlight the importance of early intervention for improving road safety. The study discusses the implications of these findings for understanding the behavioural underpinnings of the decrease in crash involvement observed in the early months of driving.