Research On Predicting Models Of Vehicle Operating Speed In Plateau

Operating speed is one of the important parameters to evaluate the consistency of geometric design.At present,there have been a large quantity of studies on the operating speed prediction models,while lacking consideration of the impact of altitude.The special natural and geographical environment in high altitude area has a significant influence on both vehicle dynamic performance and the driver’s physiology and psychology,which in turn affects the operating speed of vehicles.Therefore,existing operating speed models are not applicable to the plateau.This paper studies on the models of operating speed in plateau,aiming to provide technical support for evaluation of consistency of geometric design in plateau.Firstly,the main factors relating to the environment in plateau which influence operating speed and acceleration are discussed based on research results of operating speed models and power performance of vehicles at home and abroad.Secondly,this paper studies the characteristics of operating speed in plateau,on this basis,the expected speeds of vehicles at different design speeds are calibrated with the measured operating speed data.By comparing operating speeds at starting and ending points of tangents with gradients ranging from 0 to 4%,this paper puts forward a division criteria of tangent sections catering for plateau based on the disparity of sensitivity of operating speeds to gradients.Accordingly,models were developed to predict operating speed of vehicles and trucks on tangents in plateau.Then this paper analyses the relationship between operating speed at the starting point of curves and approaching sections and introduces the regression model of reduction of operating speed at the starting point of curves,which is related to radius and speeds.Accordingly,models were developed to predict operating speed of vehicles and trucks on curves in plateau.Finally,the validity of built models is estimated by variance test,and the predicting models in this paper are compared with those in specification of evaluation of road safety.