Applying Time-to-Collision to Enhance the Coefficient of Determination for GHR Car-Following Model in Deceleration Mode

Car-Following models are integral parts of capacity analysis, safety research, traffic simulation, and developing advanced vehicle control systems. During the past six decades, various car following models have been developed. GHR is the most well-known stimulus based model, in which the stimulus is the relative velocity of vehicles. In this research, timeto- collision (TTC), as the stimulus, is proposed as a substitute for relative velocity in the GHR model. GHR model is calibrated based on the comprehensive and detailed data gathered in the NGSIM project on I-80 freeway. The Results of GHR model calibration based on the data obtained for the two stimuli indicated that coefficient of etermination (R2) increased from 0.233 in the base model to 0.638 in the proposed model. In all, the results indicated that the application of TTC as the stimulus in the GHR model would improve the model's outcome.