The US Department of Transportation’s National Highway Traffic Safety Administration (NHTSA) has issued a Notice of Proposed Rulemaking (NPRM) to revise the Federal Motor Vehicle Safety Standard for accelerator control systems (ACS) to ensure drivers can better stop a vehicle without extraordinary driver actions in the event of either (1) accelerator control system disconnections; or (2) accelerator pedal sticking and entrapment.
NHTSA proposes to amend the Standard to address more fully the failure modes of electronic throttle control (ETC) systems and also to include test procedures for hybrid vehicles and certain other vehicles. This part of today’s proposal is related to an NPRM that NHTSA published in 2002.
This requirement would apply to passenger cars, multipurpose passenger vehicles, trucks and buses, regardless of weight.
NHTSA proposes to add a new provision for a brake-throttle override (BTO) system, which would require that input to the brake pedal in a vehicle must have the capability of overriding input to the accelerator pedal. NHTSA would apply the requirement for BTO systems to new passenger cars multipurpose passenger vehicles, trucks and buses that have a gross vehicle weight rating of 10,000 pounds (4,536 kg) or less.
The BTO proposal is an outgrowth of NHTSA’s research and defect investigation efforts aimed at addressing floor mat entrapment and related situations. NHTSA research indicates a BTO requirement will help reduce the risks of high-speed unintended acceleration and prevent crashes involving a stuck or trapped accelerator pedal by allowing the driver to maintain control through normal application of the vehicle’s brakes.
Controlling acceleration is one of the fundamental tasks required for safe operation of a motor vehicle. Loss of control of vehicle acceleration and/or speed, so-called “unintended acceleration” or “UA”, can have serious safety consequences. It can arise either from driver error or for vehicle-based reasons including accelerator pedal interference and separation of throttle control components.
To address loss of control of vehicle acceleration, FMVSS No. 124 requires an engine’s throttle to return to idle when the driver stops pressing on the accelerator pedal or when any one component of the accelerator control system is disconnected or severed at a single point...In recent years, NHTSA has been working to update FMVSS No. 124 to more directly address newer electronic engine control systems and also to address different types of accelerator control safety issues such as those that could be mitigated by BTO technology.—NPRM