Introducing automatic control method of speed limit signs safety standards before horizontal curves via Mobile Mapping System

Compilation of appropriate strategies for the improvement of road safety requires full data of the road specifications. The use of Mobile Mapping System as a method for the road safety audit is a trend that provides a comprehensive database of information including video images and geographical information. The goal of this paper is to introduce an automatic method which can control the safety standards related to speed limit signposts before the curve by analyzing the collected data and maintain sufficient accuracy in controlling the safety standards and economize on time and cost. The proposed method analyzes the coordinates of the centerline axis points of the road and determines the geometrical specifications of the horizontal curves in first phase and processes the images in order to identification and distinction of the speed limit signs before the horizontal curves in second phase, finally safety standards related to placement and limitation of speed sign before the curve is controlled. The final results substantiate a high percentage of success in identification and accuacy in the analyzing of geographical date phase and image processing phase. The accuracy of the proposed method for horizontal curves was proved to be 90% for the horizontal curve radius calculation and it was 97% for the beginning point of the horizontal curve determination. Besides application of support vector machine leads to 92% accuracy in identification of the signs and 97% accuracy in speed limit distinction.