Thermal Imaging Safety Screening System for Commercial Vehicle Brakes - Factsheet
A prototype thermal imaging safety screening system (TISSS) for commercial vehicle brakes was designed, constructed, and tested for use in selection of commercial vehicles for safety inspections at Georgia weigh stations. The TISSS allows an operator at a weigh station to view the relative temperatures of brake drums seen through the wheel rims of commercial vehicles. The infrared (IR) image of a correctly operating brake system shows all brake drums to be hot and approximately the same temperature when the vehicle is braking. Where a brake is defective, the brake drum appears to be the same temperature as the wheel rim and darker than a properly operating brake. The TISSS was developed using commercial, off-the-shelf components and advanced IR image acquisition, processing, and storage.
The TISSS was deployed on I-20 near Atlanta at the Douglas County weigh station. The TISSS was deployed over a one-month period (April 2002) in three configurations:
The first two configurations required a dedicated operator from research staff and screened all vehicles entering the station. In the third configuration, the assembly screened only those vehicles being weighed and was operated by a weigh station operator concurrent with weighing operations. In all three configurations, a PC-based video capture system allowed viewing, storage, and printing of selected images. Wireless radio links were used for video capture at the first two configurations. A hardwired version of the TISSS was also designed which would include conduit between the video camera and PC.
The prototype was effective in detecting brake problems, and operator training was minimal. The third configuration proved to be the most effective, and the system was used in this configuration at the I-20 weigh station for six months after the evaluation with no problems. Use of the system was deferred due to storage limitations at the station.
Although a smaller number of vehicles are screened in the third configuration, consistent screening is facilitated in this configuration which may not be provided using a dedicated operator at the entrance ramp. Automation of the process may be possible using machine vision technology and integration of the system with weigh station directional sign control circuitry. The goal would then be to screen each vehicle in passing on the entrance ramp, select which vehicles to inspect, and automatically route suspect vehicles to the rear of the station via existing overhead signs.
Mr. Gary L. Hoffman
Pennsylvania Department of Transportation