INTRODUCTION OF INTELLIGENT VEHICLE DETECTION SENSORS

The traffic control system of the Metropolitan Expressway is in operation 24 hours a day, 365 days a year, collecting and processing traffic data obtained from vehicle detection sensors installed along the highway. This traffic data is then offered to the users of the highway as information on required travel time, congestion and the like. There are several types of vehicle detection sensors available, but most of the sensors installed along the Metropolitan Expressway are ultrasonic sensors. The reason for this choice is that these ultrasonic vehicle detection sensors can be easily installed along the side of the highway, thus facilitating easy maintenance compared with other types of sensors, and it is also superior from an aesthetic viewpoint. However, there have been several problems associated with previous types of ultrasonic vehicle detection sensors: (1) in tunnels and on three lane sections of the highways, previous types of sensors detected vehicles erroneously due to the reception of unnecessary reflected signals which caused a decrease in the accuracy of detection; (2) due to the fact that there are more than 2,085 sensors installed, the load on the maintenance department was excessive; and (3) speed measurement errors were high when measuring high-speed vehicles. This report is an outline of the intelligent vehicle detection sensors (hereafter, I Type vehicle detection sensors) introduced to solve these issues. For the covering abstract see IRRD E102946.