The Problem

Despite advances in commercial vehicle safety technology, vehicle brakes remain a common cause of accidents, injuries, roadcalls, and mechanical breakdowns. In the United States there are over 480,000 truck and bus crashes annually[1] with almost 30% of them involving brake failure as a factor[2]. Every year about 15% of all commercial vehicles are placed out of service after inspections because of brake-related violations[3]. Brake related roadcalls and unplanned maintenance in transit agencies can exceed several per day; for example, in 2010 WMATA averaged 3 brake-related roadcalls per day[4], in 2005 Miami-Dade averaged 2 brake-related roadcalls per day[5], and in 2013 Montgomery County MD averaged over 1.5 brake-related mechanical failures every week[6].

1 out of 7 trucks are placed out of service from bad brakes – every day

Commercial vehicle brakes require invasive and time consuming manual inspection to detect issues. This is because many critical components face each other with only millimeter sized gaps, requiring disassembly for visual inspection. Because of this, vehicle brakes are usually not disassembled and fully inspected more than twice a year, long enough for problems to occur without notice between inspections.

The Solution

Vehicle brakes emit ultrasonic energy (acoustic frequencies above what humans can hear) as part of the friction process; the spectra of these sounds are highly dependent on the mechanical condition of the brake and can be used to detect specific types of problems.


    1. Vehicles drive by roadside ultrasonic sensors


    2. Sensors automatically capture ultrasonic brake emissions as vehicle passes by

3. Automated vehicle and problem identification

4. Problems logged and alerts issued to fleet managers, maintenance and inspection personnel, and dispatch/drivers

BrakeAudit’s ultrasonic-based brake monitoring systems consist of non-invasive sensors placed roadside near exits of vehicle facilities. The sensors are automated to provide daily analysis of brakes for every vehicle and issues alerts if problems are detected. The data can be used to optimize maintenance schedules based on the conditions of the brakes.


[1] U.S. Department of Transportation, Federal Motor Carrier Safety Administration, Large Truck and Bus Statistics, 2014.
[2] U.S. Department of Transportation, Federal Motor Carrier Safety Administration, Report to Congress on the Large Truck Crash Causation Study, 2009.
[3] Commercial Vehicle Safety Alliance, CVSA Releases Results from Brake Safety Day, November 2017.
[4] 2010 MetroBus Fleet Management Plan, Washington Metropolitan Area Transit Authority, 2010.
[5] Metrobus Fleet Management Plan, Miami-Dade Transit, 2005.
[6] Ride On Bus Fleet Management Plan, 2013 to 2020, Maryland Transit Authority and Montgomery County Department of Transportation, 2014.