The federal National Highway Traffic Safety Administration (NHTSA) is proposing minimum sound requirements for electric cars, hybrids and other vehicles in order to warn pedestrians, cyclists and the sight-impaired. The rule is based on a 2009 NHTSA study of state-level accident data finding that 77 of 8,387 hybrid vehicles (.9 percent) were involved in crashes with pedestrians and 48 (.6 percent) in accidents with bicyclists. For conventional vehicles .6 percent were involved in accidents with pedestrians and .3 percent with bicycles.

As the NHTSA sees it, hybrids are twice as likely to be involved in pedestrian or bicyclist accidents at low speeds when the internal combustion engine is not running. The statistics did not represent all accidents nationwide and the crashes could have been caused by several factors, most notably inattention. The NHTSA concluded that cars needed to be noisier.

The federal bureaucrats will now require automobile manufacturers to install some kind of speaker system enabling the vehicles to be detectable when travelling less than 18 miles per hour, even when street and background noises are present. The rules will begin with the 2016 model year and cost manufacturers $23 million the first year of production. Heavy-duty vehicles and motorcycles are included. What vehicle owners, or the public, think of the rule does not appear to have been a consideration.

Manufacturers will reportedly enjoy flexibility to use different sounds, perhaps a recording of a Harley-Davidson chopper, a jackhammer, or maybe Sam and Dave belting out “Hold On, I’m Coming.” Perhaps carmakers will advertise their vehicles as “20 percent louder than NHTSA minimum noise standards.” The police may find here a new revenue source, fining drivers for excessive silence, insufficient noise, or a defective external speaker system.

It remains an open question whether federally mandated gadgetry will improve safety, which depends ultimately on driver and pedestrian vigilance, and factors such sobriety. An external speaker blasting according to NHTSA specifications could well motivate a driver to be less vigilant. On the other hand, such regulations help to keep federal bureaucrats in business. They surely know that many conventional vehicles are whisper-quiet and difficult to hear approaching. It would come as no surprise if the NHTSA, with an eye to its budget, extends the mandatory noise rule to all vehicles.