Development of car-crash accident simulator based on Petri nets and its application to anti-accident measures for dangerous points

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(1) Development of plot-type simulator with built-in car-crash risks :We have developed Petri-net traffic simulator (PETS) for traffic congestion analysis and its countermeasures. In this development, we paid much attention to ensure safety traffic flows anywhere in road network and built two types of mechanisms, named as autonomous and forcec type, in our proposed Petri nets representations of traffic flows. These mechanisms will collapse by connection of called killer nets. Here we develop nets of "suddenly birth of token", "fade-out of token", and "non-marking of token"as killer nets. We also develop a net that detects and normalizes accident situation and allow s us to continue simulation. Car-crash simulation nets can be constructed by connection these two type nets with car traffic nets and can directly be executed by our PETS software.(2) Development of Driver's Action Process Sub-net :To refine collapse of safety mechanisms, we first take into consideration of birth of risky oc … More casions at dangerous points and describe them as colored tokens corresponded to their intensity in driver's action process net. Secondly, we assume that driver could take emergency breaking according to circumstantial judgement and modify the connection of newly developed driver's net to car-running sub-net as taking emergency breaking both as recovery of broken safety mechanism and as occurrence of hazard for following cars. We also here include function of driver's caution in this process net(3) Results of Rear-end Collision Accident Simulation :We construct traffic flow net by connecting two set of driver's sub-net to car-running sub-net that represents a lane of 130〜200 m. And we do some simulation of rear-end crash accident, as assuming that the traffic volume is 15 (vehicle/min) and the birth rate of occasion is high, and show that expansion of minimum distance between cars and suppression of acceleration desire both contribute to reduce the means of number of accidents in our simulation system. We also demonstrate that if we success to expand driver's caution we could reduce the number of accident as remarkably. We need expand our method to head-on and right-turn accident at intersection. We also need include characteristics of elderly and young driver's sub-net. Less