MODELING LEAD VEHICLE DYNAMICS THROUGH TRAFFIC SIMULATION AND FIELD DATA

The majority of existing driver-behavior and carfollowing data sets, upon which many models are based, are relatively old and focus primarily on the following vehicle instead of the lead vehicle. Therefore, the purpose of this study was to look at how lead vehicle speed varies along basic uniform roadway segments, with grade and with horizontal curvature in the microscopic traffic. The simulation results showed that lead vehicle speed will remain constant under any circumstances, irrespective of slope or grade, or road type. The simulation results may not, however, reflect real lead vehicle dynamics in the real world. The behavior of a lead vehicle at an intersection with a traffic signal was also investigated. When approaching a red light, a linear regression was drawn between lead vehicle deceleration distance and its original speed, i.e., the speed before deceleration. The study showed that at higher roadway speeds, more lead vehicles slowed down to pass the intersection with a green light. Moreover, this study examined how a change in speed for all vehicles in a curve is caused by the change in speed of the lead vehicle. The study, calibrated using field data, was carried out by an Application Programming Interface function in the advanced simulation model, namely AIMSUN. The results showed that if the speed of all of the lead vehicles is influenced by roadway curvature, i.e., there is a reduction in speed, the overall average speed of the traffic network will be affected in the same manner regardless of the volume and speed limit.