In Fuzzy Logic Model, membership functions of input and output parameters are determined based on survey results of a particular area and by the help of an expert’s knowledge. For input parameters (travel time, traffic safety, congestion and environmental effects), triangular and trapezoidal membership functions are used, while for output parameter (route utility), triangular is used (Figure 7). Most convenient membership functions are defined by examination of statistical dispersion of the survey results and after some trials.