Studies On Driving Safety Zone Of Conflicts Between Vehicles And Pedestrians At Non-signalized Crosswalks

There is a rather high conflict frequency between vehicles and pedestrians at crosswalk without signals on urban roadways.Thus,studies on this kind of conflicts are of great significance,which can not only provide effective theoretical arguments for driving assistance systems,but also improve the traffic capacity of road section and the safety of pedestrians when crossing streets.Firstly,driving perception behavior is reviewed based on the analysis of driver information processing.Driving safety zone is explored according to longitudinal and lateral movement and the domestic and international research of the safety characteristics.The application of driving safety zone in the driver assistance system is analyzed.Research data are all collected from real traffic situations,and vehicle braking characteristics,driving behavior and traffic environment are considered in the data acquisition.To reveal the interaction between drivers and pedestrians,three crosswalks without signals in Beijing are chosen to be observed and videoed,and trajectories of vehicles and pedestrian are obtained based on the image processing.Parameters like the initial speed before decelerating,deceleration position and position to the conflict point are investigated.Traffic conflicts are divided into three categories based on the deceleration behavior(initiative deceleration,impulsive deceleration and abrupt acceleration and deceleration when drivers realize that there is a conflict risk).Variation of speed and position of vehicles and pedestrians are analyzed proper analysis of deceleration behavior is given under different situations.Based on SOMK clustering method,observation data are clustered in terms of three kinds of parameters: TTC、PET and DST.Based on the different perception of conflict risk,the conflict severity is divided into three levels,low risk,medium risk and high risk conflict.Kinetic characteristics of vehicles and pedestrians under different conflict levels are studied,the relationship between conflict severity and longitudinal and lateral distance is established.The distribution of longitudinal and lateral distance under different conflict severity is presented,which is the boundary conditions to determine less safe zone,less dangerous zone and dangerous zone.In this research a new method is provided for the determination of driving safety zone.