Proportion of vehicles moving freely depending on traffic volume and proportion of trucks and buses

Adequate description of traffic in all intersections where traffic is not controlled by traffic lights is substantially affected by the adopted model of proportion of vehicles which move freely in traffic flow. The present study attempts to evaluate the proportion of vehicles moving freely in traffic flow depending on traffic volume and the effect of proportion of trucks and buses on this parameter. The analyses were carried out with an example of flows of vehicles moving in small roundabouts. It was observed based on the results of the analyses that the proportion of vehicles moving freely in traffic flow depending on traffic volume is best characterized by a spline, composed of three components which include quasi-free traffic, uniform traffic and non-uniform traffic.