Presenting a New Model Based on Fuzzy Logic to Specify theSpeed Limit for Passing Traffic Proportional to ImmediateConditions of Thoroughfares

The safety criterion plays an important role in increasing the reliability andoperation of transport network. In this regard, there are many parametersinvolved in safety of roads network; one of the most important ones is the speed.As recent studies suggest, about 35 % of road casualties are due to driving overthe speed limit. Now, if we explore the main reason why drivers don’t observethe speed limit, it turns out that most drivers take the speed limit to beunsystematic, believing it shouldn’t be fixed for driving in every condition;rather it should be variable depending on environmental and road conditions .Describing how decision-making methods are used in fuzzy environment- whichis suitable for addressing the ambiguous and multifaceted notion of determiningspeed in order to specify the strategy of speed limit determination is the mainpurpose of this paper. Therefore, this paper tries to present a model based onfuzzy logic, by identifying the factors affecting the speed limit determination ofthe roads (e.g. the road, weather condition, visibility on the road, the traffic scale,…) and converting these factors to verbal variables. Such a model can create anappropriate platform to carry out the engineering calculations of speeddetermination based on quality of conditions. Ultimately, this would arouse thesenses of drivers, and reduce accidents casualties and lessen problems of urbanand peri-urban transportation.

Presenting a New Model Based on Fuzzy Logic to Specify theSpeed Limit for Passing Traffic Proportional to ImmediateConditions of Thoroughfares Keywords:

Speed Limit , Fuzzy Logic , Verbal Variables , Traffic Speed Management , Engineering Calculations