Determining Optimal Critical Junctions for Real- time Traffic Monitoring for Transport GIS

Traffic data is the most important component of any transport GIS. They are mainly collected by traffic sensors (detectors). However, the installation of sensors is quite expensive. There have been studies on the finding of optimum location of inductive loop detector, the most widely used sensor in the past decades. However, with the advancement of new sensor technologies in recent years, many new sensors are now available for multi-lane and multi-direction traffic monitoring. Most of them are nonintrusive sensors which are more suitable be located at road junctions instead of roadways. Thus, different from previous studies on link-based sensor location, this paper explores method in determining critical road network junctions for the optimum location of nonintrusive sensors for monitoring and collecting real-time traffic data. The objective is to select the least number of junctions while maximally cover the road network. Since the problem is NP-complete, a greedy-based heuristic method is proposed and a numerical experiment is conducted to illustrate its efficiency.