New model for passing sight distance on two-lane highways

The maximum permitted length of trucks in North America and other parts of the world has increased significantly over the past 20 years. This has led to concern regarding the interaction of trucks with other elements in the traffic stream. There are many highway infrastructure design criteria that need to be reassessed in light of recent evidence on the behavior and properties of trucks. One of them is the passing sight distance (PSD), which is crucial for a safe overtaking maneuver. In addition, to overcome the increased congestion of modern roads, the development of the Intelligent Transportation System also requires an on-line overtaking model, which is able to provide the desired trajectory for the control. This paper presents a mathematical model that enables the determination of the safe PSD and calculates the desired trajectory for overtaking on two-lane highways. In addition to vehicle length, 10 other parameters that have an effect on the PSD are also included in this model. Specifically, the effects of various input parameters have been examined. Simulation results from this model are compared with those suggested by the American Association of State Highway and Transportation Officials (AASHTO) to test the validity of the model. Also, we explain why the standards given in the AASHTO study of 1994 could be thought to be conservative.