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NHTSA proposes new minimum sound requirements for hybrid and electric vehicles

As required by the bipartisan Pedestrian Safety Enhancement Act of 2010 (PSEA), the US Department of Transportation’s National Highway Traffic Safety Administration (NHTSA) has proposed minimum sound standards for hybrid and electric vehicles.

The proposed standard, Federal Motor Vehicle Safety Standard No. 141, would fulfill Congress’ mandate in the PSEA that hybrid and electric vehicles—including passenger cars, light trucks and vans (LTVs), medium- and heavy-duty trucks, buses, low speed vehicles (LSVs), and motorcycles—produce sounds meeting the requirements of this standard.

This proposed standard applies to electric vehicles (EVs) and to those hybrid vehicles (HVs) that are capable of propulsion in any forward or reverse gear without the vehicle’s internal combustion engine (ICE) operating. The sounds would need to be detectable under a wide range of street noises and other ambient background sounds when the vehicle is traveling under 18 miles per hour.

At 18 miles per hour and above, vehicles make sufficient noise to allow pedestrians and bicyclists to detect them without added sound.

Each automaker would have a significant range of choices about the sounds it chooses for its vehicles, but the characteristics of those sounds would need to meet certain minimum requirements. In addition, each vehicle of the same make and model would need to emit the same sound or set of sounds.

NHTSA estimates that with this rulemaking, the benefit of reducing the pedestrian injury rate per registered vehicle of hybrids to ICE vehicles when 4.1% of the fleet is HV and EV would be 2,790 fewer pedestrian and pedalcyclist injuries. NHTSA also estimates that this proposal will result in 10 fewer pedestrian and pedalcyclist injuries caused by LSVs. Thus, 2800 total injured pedestrians are expected to be avoided due to this proposal representing 35 equivalent lives saved.

NHTSA does not estimate any quantifiable benefits for EVs because the agency syas that EV manufacturers would have installed alert sounds in their cars without passage of the PSEA and this proposed rule.

NHTSA calculated a cost of $0.83 to $0.99 million per equivalent life saved across 3% and 7% discount levels for the light EV and HV and LSV fleet.

According to our present model, a countermeasure that allows a vehicle to meet the proposed minimum sound requirements would be cost effective compared to our comprehensive cost estimate of the value of a statistical life of $6.3 million.

—“Minimum Sound Requirements for Hybrid and Electric Vehicles”

The public has 60 days to submit comments on this NHTSA action.



Trevor Carlson

Are electric bicycles or even regular bicycles or any human powered vehicle subject to this regulation?


Many pedestrians with earphones full of loud metal music will not hear a steam locomotive coming. For those people, electrified vehicles would have to be equipped with sensors + some kind of directional electric shock device with 10+ m range or so?


Why not just mandate a Bluetooth signal? Pedestrians would then be responsible for having a bluetooth device, and those with cell phones, iPods, etc. would still hear the signal. That would limit noise pollution from cars in the cities.


The real fun is going to come when people re-program the sound units for personal expression.  I foresee millions of hybrids sounding like tie fighters or light sabers.

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