Abstract
A driver’s response to a front-coming vehicle collision consists of braking reaction time and braking behavior. The purpose was to investigate drivers’ responses at different speeds, relative distances, and particularly the behavior on the accelerator at the collision moment. Twelve young men participated in driving simulator tests. Vehicle parameters and electromyograms (EMGs) of the drivers’ tibialis anterior muscles were recorded and responses were analyzed. The drivers’ braking reaction time windows were divided into pre-motor time, muscle activation time, accelerator release time, and movement time. By comparing the reaction times and collision times, braking behaviors were investigated. It was found that movement times (r = -0.281) decreased with speed. Pre-motor times (r = 0.326) and muscle activation times (r = 0.281) increased with relative distance. At the collision moment, the probability of the driver’s lower extremity being on the accelerator, in the air, and on the brake pedal was 7.4%, 18.9%, and 73.7%, respectively. With higher speeds and smaller distances, the lower extremity was more likely to be in the air or even on the accelerator in different muscle activation states. The driver will collide in normal driving postures which muscles are not or not fully activated in very urgent situation.