The safety benefits of collision warning applications - Evidence from on-road data

A collision warning system (CWS) facilitates timely crash-avoidance behaviours by providing real-time warnings to drivers about imminent collisions. Despite its potential benefits in terms of both shorter response times and ability to maintain longer headways, its adoption has been slow. Smartphone-based collision warning applications (CWAs) may assist in stimulating wider adoption of collision warning technology, as they are much less expensive and are accessible in many types of smartphones. However, driver behaviour with CWAs has never been studied. Aim: This study explored the behaviour of 26 drivers in the initial 2-3 weeks of using a CWA, with respect to (1) their responses (speed behaviour) to the warnings they received, and (2) the number of warnings they received over time. Method: Drivers were asked to install a CWA on their smartphone and share their trip data in return for monetary rewards. The data logged by the CWA included instantaneous speed and the time-stamped warnings that were received during the trips. The analysis employed several linear and non-linear regression models. Results: The CWA generated safer behaviours: drivers lowered their speed when warnings were issued and maintained safer headway distance over time. In view of the high penetration rate of smartphones, it is suggested that ways to further test and use CWAs be developed.