Let us try to explain why fuzzy logic systems were developed for transportation engineering. Great many of the problems in the field of transportation planning and traffic control are often ill defined, ambiguous and vague. As already mentioned, many traffic and transportation problems, phenomena and parameters are characterized by subjectivity. It is hard to disregard the fact that subjective judgment is present in problems dealing with the choice of route, mode of transportation and carrier, a driver's perceptions and reactions, an established level of service, defining safety standards, defining criteria to rank alternative transportation plans and projects, etc. It should also be emphasized that both deterministic and stochastic models that have been developed to solve a variety of complex traffic and transportation problems are characterized by mathematics based on binary logic. Without denying the importance of binary logic as the basis for the development of many scientific disciplines and technology leading to the prosperity of man's society, we must note that it cannot deal effectively with passengers’, dispatchers’ or drivers’ feelings of uncertainty, vagueness and ambiguity. Since the fuzzy set theory recognizes the vague boundary that exists in some sets, different fuzzy set theory techniques need to be used
International Journal on Soft Computing (IJSC) Vol.3, No.2, May 2012
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in order to properly model traffic and transportation problems characterized by ambiguity, subjectivity and uncertainty.Some applications of Fuzzy Logic in transport planning are discussed below.