Abstract
Understanding car driver responses in emergency car-to-cyclist collisions is useful for developing active safety systems to reduce injuries in car-to-cyclist collisions. In this study, driver responses toward cyclists intruding into a car’s path at an intersection were investigated in scenarios with different time-to-collisions (TTC) (1.5 s and 0.8 s for the near side approach, and 2.0 s for the far side approach) using a driving simulator. The drivers’ responses to avoid collisions were braking and swerving, whereas swerving alone was not effective for avoiding collisions. Collisions occurred when the sum of braking reaction time (BRT) and car braking deceleration time was larger than the TTC when the cyclist was visible to drivers. The mean of BRT was 0.65 and 1.35 s in the near-side and far-side scenarios, respectively. The driver’s initial gaze has an important role in affecting the driver’s time to notice the cyclist. The gaze of many drivers was located on the future path (car lane) when the cyclist was visible. As the angle between the gaze direction and the cyclist was larger, the time taken for the driver to notice the cyclist was longer. As this notice time increased, the driver’s response changed consistently from swerving to braking. Through this study, a collision area is proposed using TTC and car velocity based on the collision occurrence equation.
