California Partners for Advanced Transportation Technology

This report documents a practical work conducted at California PATH for developing a portable tool to be used at the control cabinet level to accurately diagnose any fault(s) of a loop detection system (including loop circuits, loop cards, cable links, etc.), to check the detection accuracy, to deal with sensitivity of detector card, and to correct the faulty data. To achieve these functionalities at the low level, it is necessary to utilize an independent source as a baseline data to compare against the loop detection system output. Such a comparison also permits an evaluation of the loop system. Since multiple-vehicle tracking technologies using digital video camera on freeways have been well-developed and tested at PATH, it is used as the baseline measurement in the portable tool for the loop fault diagnosis. This report presents the development of a prototype system including the hardware, the software, the data communication method, and the algorithms. Some preliminary consideration has also been conducted on lower (control cabinet) level data correction and communication system reliability of several Caltrans District for sensor data passing. Future work will be on systematic loop fault detection and lower level data correct.