NEW MODEL FOR PASSING SIGHT DISTANCE ON 2-LANE HIGHWAYS

The maximum permitted length of trucks in North America and other part s of the world has increased significantly over the past 20 years. Thi s has led to concern regarding the interaction of trucks with other el ements in the traffic stream. There are many highway infrastructure de sign criteria that need to be reassessed in light of recent evidence o n the behavior and properties of trucks. One of them is the passing si ght distance (PSD), which is crucial for a safe overtaking maneuver. I n addition, to overcome the increased congestion of modem roads, the d evelopment of the Intelligent Transportation System also requires an o n-line overtaking model, which is able to provide the desired trajecto ry for the control. This paper presents a mathematical model that enab les the determination of the safe PSD and calculates the desired traje ctory for overtaking on two-lane highways. In addition to vehicle leng th, 10 other parameters that have an effect on the PSD are also includ ed in this model. Specifically, the effects of various input parameter s 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. A lso, we explain why the standards given in the AASHTO study of 1994 co uld be thought to be conservative.