Simulating Hazardous Traffic Condition for Urban Expressways -A Micro-Simulation Approach

Abstract

The remarkable advancements in the field of Intelligent Transportation System (ITS) over the past two decades have promoted several studies on improving safety aspects of acess controlled roads. As many of the expressways in the developed world are instrumented to generate adequate amount of data on the traffic condition in realtime, it is possible to monitor traffic condition more closely and identify any anomaly that can evolve into a hazardous traffic condition. The result of which leads to the formation of real-time crash prediction model. In present context ensuring pro-active road safety management plays a vital role in transportation modeling. To design a pro-active road safety management system, it is important to be able to devise a way to bring the hazardous traffic condition back to normal. In the past several studies have taken place where micro-simulation or driving simulator based approaches were adopted to achieve that. For the purpose of this study, a micro-simulation based approach was chosen. It is to be noted that driving simulator could capture individual driving behavior at a greater depth but as use of it involves a great deal of time as well as it depends on the respondents, it was avoided. Micro-simulation approach is a profound tool used by researchers to determine and analyze traffic characteristics. Micro-simulation approach gives access to car following as well as lane changing behavior of individual vehicle and allows analyzing their interactions by changing the parameters. Existing studies provided very little insight into how to simulate hazardous traffic condition. So, in this study, a detailed and step-by-step explanation on how to simulate hazardous traffic condition has been incorporated. CUBE Dynasim is a micro-simulation software developed by CITILABS which was used in this study. In CUBE Dynasim the normal traffic condition was created by using aggregated flow data obtained from Route 3 and Route 4 of Tokyo Metropolitan Expressway. The values of the parameters were altered to create hazardous traffic flow condition. Best possible result was obtained by changing the values of car-following maximum threshold and mean of threshold value for car following rules. Again, in case of lane Abstract v changing behavior changing of heavy vehicle threshold, light vehicle average time, light vehicle minimum time, light vehicle maximum time, light vehicle standard deviation, light vehicle minimum distance, heavy vehicle average time, heavy vehicle minimum time, heavy vehicle maximum time, heavy vehicle standard deviation, heavy vehicle minimum distance reflected best result. The outcome of the study was verified by comparing the field traffic flow variable data with that of the simulated data.