Inductive control is a control method in which the signal display time for each direction of an intersection is adapted to traffic demand based on the vehicle arrival status at the intersection detected by vehicle detectors. However, due to the slow vehicle speeds in the left-turn lanes and the start-stop motion of vehicles in the left-turn waiting area, radar is prone to losing targets. By deploying geomagnetic detectors to output vehicle occupancy data in the left-turn lanes and left-turn waiting area, the deficiency of radar in detecting low-speed and stationary targets can be compensated.    

Deployment Method: (1) One MPD093 radar-video-geomagnetic integrated detector shall be installed on each signal lamp pole at the four directions of the intersection, and the radar-video-geomagnetic integrated detector shall face the direction of incoming vehicles. (2) Arrange a row of virtual coils at approximately 12m, 25m, and 39m downstream from the stop line along the approach lanes for stop-line detection, extended-range detection, and free-flow detection respectively. (3) Set two rows of geomagnetic detectors in the left-turn waiting area, with an interval of 2m between the front and rear rows of geomagnetic detectors. (4) Install one geomagnetic detector at the entry point of the left-turn entrance guide lane and at the stop line respectively to detect the number of vehicles and their occupancy status. (5) The installation position of the repeater must enable it to cover the view and range of the geomagnetic detectors/radar-video-geomagnetic integrated detectors supported by the repeater. The maximum distance between the repeater and the radar-video-geomagnetic integrated detector is 310m. Therefore, the repeater can be installed at any position as long as it can provide good signal coverage to the radar-video-geomagnetic integrated detectors/geomagnetic detectors. The layout of detectors for left turn + induction control is as shown in the following diagram:

Layout Diagram of Detectors for Left Turn + Induction Control