Commercial Vehicle Brake Testing - Part 2: Preliminary Results of Performance-Based Test Program

A study to determine whether performance-based brake testing technologies can improve the safety of our highways and roadways through more effective or efficient inspections of brakes of on-the-road commercial vehicles is being sponsored by FHWA/DOT-OMC. A key objective of the study is to determine how the results from performance-based “inspections” compare with results obtained through traditional visual methods, such as those recommended by the Commercial Vehicle Safety Alliance (CVSA). Data from joint inspections (i.e., CVSA and performance-based inspections on the same vehicle), obtained over approximately a one year period, have been analyzed. Description of three of the performance-based technologies and preliminary results from approximately 1,400 joint inspections are covered in this paper.

The results from performance-based inspections show excellent correlation only with the CVSA inspection criteria that are specifically force related and only if the brake system could be tested to full capacity, i.e. high brake application pressures. At low application pressures the correlation was not as good. However, the performance-based technologies were able to detect a number of brake defects that were not found during visual inspections. While the overall results to date indicate that neither type of inspection is perfect, they suggest that performance-based brake tests have the potential to be used as both vehicle screening tools and for enforcement. However, both appropriate modifications to the test machines, and the development of enforceable standards are required for enforcement use.