تعيين زمان بهينه چراغ هاي راهنمايي زمان دار به منظور كاهش توام ريسك تصادف و زمان تلف شده در تقاطع ها و كمك به كاهش ترافيك

Determining the best time of timer traffic lights to jointly reduce accident risk and lost time at intersections and help to reduce traffic congestion

More than 94 yea rs passed from the es tablishme nto f the first traffic light in Am er ica, and after that , so many methods have invented to control traffi c light s in the best way.Despite extra features of intelligent systems in intersection management and control, today many intersections use vari able timer traffic lights and officer commands different times in different hour s ofthe day, due to the need to wide studies and access to complex technology and spend much money, but this is done according to test & mistake meth od and pers onal judgement, and maybe, selection toward policc control, increase traffi c, pollution and fuel usage and also, increase total trip time and awai ting time of pedestrians. On the other hand, previous studi es are only about determining the best time of traffic light and don ʹt consider accident risk . So, in this study, we suggest a model by combining probability density function and negative division and usc of the meaning of gravity mobil e average method, to reduce accident risk and determine the best time of traffic light. In usc of this model , in traffic light ofkhajc Abdollah st. and Abouzar st. intersection in north of seidkhandan bridge, time of red light decreases to 40s from 45s, to reduce lost time and also, reduc e accident risk lower than 5%.