Research On Drive Behavior During The Yellow Light In Urban District

In urban setting, about half of all total crashes occur at intersections’ physicaland functional areas. Majority of these intersection crashes occur during signal timetransition (from green light to red light). Thus, it is important to improve the level ofsafety during signal transition time (so-called clearance interval). It is estimated thatevery year there are at least650million drivers facing the yellow light in the sixdistricts in Beijing. Yellow light is an important part of the signal transition time. Itis imperative to do research on drivers’ behavior, the relationship between decision,position of the cars, time distribution and space distribution.We chose two typical signal controlled junctions–intersection and pedestriancrossing as examples. This research focuses on driver behavior under free-flowcondition, which means that vehicle speed below20km/h is not considered. Crashesoccurred at low speed are oftentimes associated with traffic congestion, which willnot result in injury or fatality. The weather condition is good. We don’t consider thespecial weather which perhaps has an effect on the driver behavior. Two types ofvehicles are accounted in the study; passenger car and large vehicle.By analysis two possible actions (stopping or passing intersection) at onset ofyellow light as well as associated risky driver behavior and potential type of crashes,this thesis studies driver behavior. There are three probable situations under yellowlight, which is called dilemma zone, indecision zone, and optional zone. Driverbehaviors under these three situations are analyzed in detail. In urban districtdilemma zone is uncertain, however, the indecision zone in the massive and can’t beeliminated. The rate of running yellow light is introduced in the data analysis.With the extensive video data collected at several signalized intersections, theimpact of speed and distance to intersection on driver behavior are analyzednumerically by regression models. The boundary conditions are proposed for thetwo decisions regarding stopping and passing. The time and spatial distribution ofthe indecision zone is also analyzed by statistical method. By comparison ofindecision zone at two different intersections, the research found that the spatialdistribution is different but the time distribution is very close at the twointersections. With different variables, this research reveals three types of yellow lightrunning variables: speed, distance to intersection, vehicle type, model,speed-distance and length of time models. Considering the similarity of indecisionzone at two intersections, the final adopted model incorporates all collected data anduses length of time as input variable. Through the length of time model, we foundthat the rate of running yellow light appearing the trends of “slow-fast-slow” as theincrease of length of time. The mode with only one variable-length of timeprovides easy access to data and have some value for application.The result of the research is of significance to the protection of the driversduring the yellow light.