Behavioural awareness monitoring (BAM): An on-road trial of real-time messaging to nudge drivers to avoid tailgating and adopt safer following distances

Tailgating remains a common risky driving behaviour and a major contributor to rear-end crashes. Rear-end crashes constitute the most common crash type associated with compulsory third-party claims in Queensland, Australia. Despite its prevalence and contribution to crashes, few interventions exist that seek to educate drivers about what unsafe and safe following distances are. Even fewer interventions still, exist that have been implemented on-road, and which offer real-time messaging to drivers based on their own vehicle headways. This study evaluated an innovative roadside technology that was trialled by the Department of Transport and Main Roads (TMR) to detect following distances and delivers targeted behavioural feedback through a variable message sign (VMS) to nudge behavioural change through increasing understanding of what safe following distances constitute. A quasi-experimental pre–post field trial was conducted at three sites in Southeast Queensland: two were more metropolitan-based and the other a more regionally located site. In this trial, two cameras measured vehicle headways before and after drivers were exposed to a roadside message. During the intervention phase, drivers travelling with unsafe headways received a warning message, while those maintaining safer headways received a positive message. The trial evaluation assessed the capability of the system in detecting tailgating and delivering targeted messaging, as well as evaluating drivers' following distances and speeds during the messaging period compared to the baseline phase. Across the trial, the system detected more than 2.54 million vehicles and successfully matched approximately 1.69 million vehicles between cameras. The findings showed consistent patterns of positive changes in behaviour as evidenced by significant reductions in tailgating behaviour and increases in the proportion of drivers increasing their headway in the intervention phase relative to the baseline phase. The analysis of speeds indicated that BAM significantly influenced drivers' travel speeds, though the magnitude and direction of changes varied by sites and following distance categories. These findings demonstrate the capability of BAM to accurately detect tailgating behaviour and provide real-time behavioural feedback that reduces unsafe following distances and reinforces safe driving behaviour.