Is an informed driver a better decision maker? A grouped random parameters with heterogeneity-in-means approach to investigate the impact of the connected environment on driving behaviour in safety-critical situations

The motive of sharing the information in a connected environment is to assist a driver in operational, tactical, and strategic decision making and improving driving task performance. The influence of such information assistance on driver decision making and task performance during safety-critical events is not well understood. Thus, this study focusses on understanding the impact of connected environment on the acceleration noise and the response time as indicators of task performance and the decision making involved in safety-critical events. To overcome the paucity of connected environment data, an advanced driving simulator experiment is designed and conducted. Three categories of uninterrupted information are available to drivers in connected environment scenario, namely continuous information, on-time event-triggered information, and advanced event-triggered information. The safety-critical event designed in the simulator experiment is the leader's hard braking behaviour in car-following regime. In connected environment scenario, drivers receive an advanced message for this safety-critical event. To model drivers’ decision in safety-critical situations, random parameters modelling approaches are adopted to account for the unobserved heterogeneities in drivers’ decision. Consequently, a grouped random parameters hazard-based duration model and a grouped random parameters linear regression model—both with heterogeneity in parameter means—are estimated for the response time and the acceleration noise, respectively. Results show that the acceleration noise reduces in connected environment while the response time can either increase or decrease in connected environment compared to those in the traditional environment. To better understand this mixed effect on response time, a decision tree analysis is conducted. For human factors, the results demonstrate that young drivers take more advantage of connected environment relative to the middle-aged or old drivers. Overall, drivers exhibit stable driving behaviour because they have more time to react and thus, are at low risk in safety-critical situations in connected environment.