Examining braking behaviour during failed lane-changing attempts in a simulated connected environment with driving aids

Abstract

This study examines braking behaviour of drivers assisted with driving aids in a connected environment compared to when they are driving without it during failed lane-changing attempts that often exerts more pressure on the immediate follower in the target lane in the form of hard decelerations, which increases crash risk. To achieve this aim, the CARRS-Q Advanced Driving Simulator is utilised, where 78 participants faced a failed-lane-changing attempt of a lane-changer from the adjacent lane into two randomised driving conditions: (a) baseline (without driving aids); and (b) connected environment (with driving aids). A descriptive analysis of braking profiles reveals decreased decelerations among drivers in the connected environment, compared to when they are driving in the baseline condition. To model braking behaviour, more specifically the time taken by drivers to reduce their initial speeds to the minimum speeds, a grouped random parameters hazard-based duration model is developed. Factors found to significantly impact the braking behaviour are initial speed, spacing, maximum deceleration, driving condition, driver age, and gender. The developed model reveals that drivers’ braking times may increase or decrease in the connected environment compared to those in the baseline condition. However, a majority of drivers in the connected environment tend to reduce speeds earlier with a lower deceleration rate, exhibiting smoother speed reductions and larger safety margins. A decision tree analysis reveals that middle-aged and male drivers take longer to reduce their speeds in the baseline condition but shorter in the connected environment. This study concludes that followers in the connected environment respond to failed lane-changing attempts more swiftly, thereby increasing safety margins.