Abstract

Speed limit signs are posted alongside the roads based on the geometric characteristics of the roads, excepted drivers’ behaviors, and possible environmental conditions, to reduce traffic hazards to a regularity sign group. This study summarizes the results obtained by 527 questionnaires that were given to the drivers of the vehicles moving on the Chaboksar-Ramsar road, north of Iran, in December to January. About %9/5 of the drivers are female. The research is a theorical–practical type. The data collected by random choosing in statistical. The drivers answered voluntary to questions after stop about te minutes for all questions. First, we did do descriptive statistical. In second step, using classification and regression tree (CART) technique, the most important factors affecting the drivers behavior and attracting their attention to the 50km/hr speed limit sign, among the 16 such factors (Age, Gender, Education, Income, Marital status, Occupation, Driving speed, Driving time, Driving hours, Vehicle type, Number of accident during 5 years ago, Driving certificate type, Driving experience, The years of driving certificate taken, Sunglass using) identified, were found to be driver’s education and monthly income, and type of vehicle. The CART is a nonparametric model and capable for the categorical variables in various science. The parameters are known in most past studies. The results indicated that three parameters are important than other parameters but not the other parameters are unimportant in driving behavior. To validate the results, a speed limit sign near the study location has been used. The speeds of a sample of 414 vehicles were observed by the speedometer installed on the asphalt pavement at this location. The results show that the drivers do not pay sufficient attention to the posted speed limit sign. We suggest that the researchers can evaluate other models on same zones and compare the results with it.