Mirror-based perception: are male drivers accurately estimating the distance and speed of motorized two-wheelers?

Improving safety during interactions between motorized two-wheelers (MTWs) and cars is one of the critical aspects for enhancing the road traffic environment. As reported, the most frequent MTW crashes occur when cars pull out in front of an oncoming MTW, often due to conspicuity issues and driver perception errors. While existing studies have focused on perceptual error estimation from pedestrians' and drivers' perspective using static visual images and short video clips, the current instrumented vehicle-based study attempts to examine drivers' perceptions in estimating distance (Experiment 1) and speed (Experiment 2) of an approaching MTW while checking side- view mirrors in dynamic traffic environments.

A total of 28 licensed professional car drivers of varying ages were considered for this study. For data collection a camera was mounted on the MTW; and two cameras, a VBOX data logger with GPS, were installed in the car. The glance duration data were collected using driver-facing camera. Additionally, non-parametric test methods were adopted to analyze the mirror effect on drivers' perception.

The results of the study indicate that drivers generally tend to overestimate distances while underestimating speeds of motorcycles. Both the distance and speed estimation accuracy decrease with increasing driving speed as well as the longitudinal gap between the vehicles. The perception errors are observed to be more significantly noticeable at higher speeds exceeding 40 kmph or when the MTW is in the farthest distance category. Interestingly, our study also indicates that shorter mirror glance duration may contribute to these higher perception errors. The results were consistent for both the side-view mirrors, although the errors were more pronounced in the passenger's side mirror, highlighting the possible impact of longer eye-to-mirror distance.

Due to perception errors, MTW riders often think that they had ample time and space for maneuvers, leading to risky decision-making and increasing potential collisions. Our findings emphasize the effect of mirror usage in decision-making tasks while driving, underscoring the necessity for enhanced driver training programs and redesigned mirror curvature to make a safer road environment.