This study evaluated an Infrared Screening Inspection System (IRISystem) used to check commercial motor vehicles (CMVs) for brake problems. The technology used infrared cameras housed in mobile vans to monitor traffic entering and passing highway weigh stations. The cameras were able to detect temperature variations in truck wheel and brake components as heat friction was generated from brake applications. Normal brake functions produced white “hot” areas on the infrared images; non-functional brakes produced dark “cold” images.

Four states (Georgia, Kentucky, North Carolina, and Tennessee) participated in the IRISystem evaluation for a duration of one year. Three hundred and thrity (330) CMVs were subject to CVSA Level-1 safety inspection after being screened by the IRISystem, and 64 other CMVs were chosen for a follow-up CVSA Level-1 safety inspection even though they did not exhibit brake problems during the initial IRISystem screening.

RESULTS

• Approximately 10 percent of wheels screened by the IRISystem (399 out of 3769) were cold.
• Approximately 1 percent of the wheels screened by the IRISystem (44 out of 3769) were excessively hot.
• Approximately 59 percent of vehicles identified as problematic by the infrared IRISystem were placed out of service after a subsequent Level-1 brake inspection. 80 percent of these vehicles had brake problems.
• Most brake problems identified by the IRISystem were located on trailer wheels located on the far side of the CMV (with respect to the IRISystem van). It was noted that the far side wheels were easier to test because of better viewing angles and longer viewing times. Also, wheel covers on the near side obstructed views of brake components.

In addition to screening CMVs on weigh station entrance ramps, the IRISystem operators attempted to screen trucks on the highway mainline. The operators determined the camera was unable to provide useful results for trucks traveling at speeds greater than 55 miles per hour.