The US Department of Transportation's National Highway Traffic Safety Administration (NHTSA) is adding a sound requirement for all newly manufactured hybrid and electric light-duty vehicles to help protect pedestrians. The new standard, Federal Motor Vehicle Safety Standard No. 141, responds to Congress’ mandate in the Pedestrian Safety Enhancement Act of 2010 (PSEA) that hybrid and electric vehicles meet minimum sound requirements to provide an audible alert for blind and visually-impaired pedestrians.
The new federal safety standard will help pedestrians who are blind, have low vision, and other pedestrians detect the presence, direction and location of these vehicles when they are traveling at low speeds, which will help prevent about 2,400 pedestrian injuries each year once all hybrids in the fleet are properly equipped.
Under the new rule, all hybrid and electric light vehicles with four wheels and a gross vehicle weight rating of 10,000 pounds or less will be required to make an “alert sound”—which is defined as a vehicle-emitted sound that enables pedestrians to discern the presence, direction, location, and operation of the vehicle—when traveling in reverse or forward at speeds up to 30 kilometers per hour (about 19 miles per hour). At higher speeds, the sound alert is not required because other factors, such as tire and wind noise, provide adequate audible warning to pedestrians.
The PSEA specifies several performance requirements for a minimum sound that would enable visually impaired and other pedestrians to reasonably detect EVs/HVs operating below their crossover speed, including the following:
It must be sufficient to allow a pedestrian to reasonably detect a nearby EV or HV operating at constant speed, accelerating, decelerating, and operating in any other scenarios that NHTSA deems appropriate.
It must reflect NHTSA’s determination of the minimum sound level emitted by a motor vehicle that is necessary to allow visually impaired and other pedestrians to reasonably detect a nearby EV or HV operating below the crossover speed.
It must reflect NHTSA’s determination of the performance requirements necessary to ensure that each vehicle’s sound is recognizable to pedestrians as that of a motor vehicle in operation.
In addition, the PSEA requires the following:
The sound must not be dependent on either driver or pedestrian activation.
Manufacturers must be allowed to provide each vehicle with one or more sounds that comply, at the time of manufacture, with the safety standard. Each vehicle of the same make and model must emit the same sound or set of sounds.
Manufacturers must be prohibited from providing any mechanism for anyone other than the manufacturer or dealers to disable, alter, replace, or modify the sound or set of sounds emitted from the vehicle. Under the PSEA, a manufacturer or a dealer, however, is allowed to alter, replace, or modify the sound or set of sounds in order to remedy a defect or non-compliance with the safety standard.
Manufacturers have until 1 Sept. 2019, to equip all new hybrid and electric vehicles with sounds that meet the new federal safety standard. Half of new hybrid and electric vehicles must be in compliance one year before the final deadline.