Analyzing the Legibility Index of Information Signs in Highways Based on the Modeling Approach

Information signs are the main devices which inform drivers to navigate their vehicles on the roads. This process, of course, should be done through the shortest possible time. The size and font of the signs’ text should be suitable regarding the location of signs and speed of vehicles passing through. Much research has been carried out on Latin fonts but there is no available legible model for Persian fonts. One of the main problems in the evaluation of signs’ font is appropriateness regarding the speed of vehicles passing through these boards and the legibility process, including visibility, reading sign information and confirmation on driver’s mind as a matter of quality. This research presents a model to reform the process of transferring reading Persian signs’ quality to quantity which could be measured by diagrams. The main phase of the process is about visual sense functioning, whereas cameras are made on the basis of visual sense, and have been used instead of human eyes. A model is abstracted by capturing images of a sign from different distances (every 10 meters) to measure the sign’s criteria. This model is a linear equation including the relationship between the sign’s visibility distance and the height of the first Persian alphabet, that is, " ا " (called alef). In this research, all the stages of reading a sign by drivers and the needed time for each stage are illustrated on the diagrams.