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U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation

Understanding the Safety Impacts of Electronically Controlled Brake Systems in Commercial Motor Vehicles

Project Goal:

To perform an in-depth literature search for data or modeling to determine the impact of brake-by-wire systems on safety (e.g., reduced crashes, injuries, and fatalities).


Brake-by-wire systems provide electronic activation of all braking system components. These systems rely on the use of electronically-controlled communications systems already existing within single-unit trucks and between the towing vehicle and trailer.

Brake-by-wire enhances braking precision, whereas conventional braking shortens braking distance. Furthermore, brake-by-wire systems offer potential safety benefits due to their advanced integration with antilock braking systems, electronic stability control systems, and similar electronically-controlled technologies. Finally, EBS manufacturers (such as WABCO) cite significant cost savings associated with implementation of brake-by-wire systems, due to optimized wheel brake lining wear and other maintenance-related benefits.


The National Highway Traffic Safety Administration’s (NHTSA’s) Federal Motor Vehicle Safety Standard (FMVSS) 121 requires use of a pneumatic system for foundation brakes. NHTSA has already done some feasibility testing on brake-by-wire systems. By quantifying the safety impacts of such systems, FMCSA may be able to persuade NHTSA to revise FMVSS 121 to allow for brake-by-wire systems in commercial vehicles, potentially increasing the safety of such vehicles on public roads.




         Virginia Tech Transportation Institute

Last updated: Wednesday, December 8, 2021