An Alternative Regression Model of Speed-Occupancy Relation at the Congested Flow Level

Abstract

The speed-occupancy, flow-speed-and flow-occupancy models are the essential mathematical equations of the traffic engineering, which provide the road characteristics. In the speed-occupancy models, the speed is presented as dependent, and the occupancy as independent variable. The flow-speed and flow-occupancy models can be derived from the speed-occupancy model. In that case, at the speed-occupancy model, the concept of "dependency" or "independency" of the variables, which is been calculated with the simple regression method, is crucial. However, the dependency of the speed-occupancy model variables is not taken into account at the flow-speed model. At this study, an alternative regression model, which determines the flow-speed model more accurately when it is derived form the speed-occupancy model, is proposed. As the behaviour of traffic is different at the free and congested flow levels, this study is focused on the congested flow level, which is more important for the road studies.