A STUDY OF TRUCK DRIVER DECELERATION INITIATION BEHAVIOR

Abstract

This project aimed to study truck drivers’ behavior at deceleration initiation based on data collected in the euroFOT project. It was executed in two steps: statistical description of each driver’s typical deceleration behavior under normal conditions and then testing of quantitative models predicting time of deceleration initiation. The obtained results show that drivers typically achieve harder deceleration by depressing the brake pedal, while milder decelerations are carried out through releasing the accelerator pedal. A rather clear boundary was found: When the average value of acceleration during a deceleration was below -0.2 m/s2, drivers tended to used the brake pedal. Another interesting statistical observation is that most drivers had an individual, clearly identifiable typical brake pedal position 0.5 s after initiation, and the steady control over brake pedal would last at least for 2 s. As a preparation for the model testing phase, decelerations were further classified into three scenarios: lead vehicle stationary (LVS), lead vehicle moving (LVM), and lead vehicle decelerating (LVD). However, carrying out such as classification was found non-trivial, and the classification results were found to rely entirely on threshold parameters for which there were no obvious optimum values. In the model testing phase, several models were tested such as a model assuming driver’s deceleration initiation is reacting to brake lights of lead vehicle, an inverse time-to-collision (iTTC) model developed by Kiefer et al. [1], a kinematic model proposed by Gipps [2], a classical kinematic equation with constant deceleration, etc. Inspired by Flach’s perspective [3] of optical variables, a new optical model was developed based on the constant deceleration kinematic equation. The new optical model seems promising.