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EVs Must Be 'Heard on the Street' to Protect Pedestrians
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January 10, 2013

EVs Must Be 'Heard on the Street' to Protect Pedestrians

By Cheryl Kaften
TMCnet Contributor

Back in July 2011, Ford Motor Company (News - Alert) posted a note on Facebook about its efforts to make the 2012 electric Focus, ahem, “resonate” with consumers. The automaker was responding to newly proposed federal regulations, which would require “all unobtrusively quiet vehicles”—including EVs and hybrids (HEVs)—to hum, whir, or thrum so that they could not be missed on approach at speeds of 18 miles per hour or less. The goal: To give a gentle heads-up to unwary pedestrians and the visually impaired, but not to cause a ruckus.

Electric and hybrid vehicles do not rely on traditional gas or diesel-powered engines at low speeds—making them much quieter than cars that use internal combustion engines and their approach difficult to detect. The proposed standard, Federal Motor Vehicle Safety Standard No. 141, would fulfill Congress' mandate in the Pedestrian Safety Enhancement Act of January 2011 that hybrid and electric vehicles meet minimum sound requirements. Under the PSEA, the added sound also must be “recognizable” as that of a “motor vehicle” in operation.

The National Highway Traffic Safety Administration (NHTSA) estimates that, if this proposal were implemented, there would be 2,800 fewer pedestrian and pedal cyclist injuries over the life of each model year of hybrid cars, trucks and vans and low speed vehicles, as compared to vehicles without sound.

"Safety is our highest priority, and this proposal will help keep everyone using our nation's streets and roadways safe, whether they are motorists, bicyclists or pedestrians, and especially the blind and visually impaired," said U.S. Transportation Secretary Ray LaHood, in a statement.

Now, the NHTSA has completed due diligence on the proposal, releasing the report, “Minimal Sound Requirements for Hybrid and Electric Vehicles—Draft Environmental Assessment.”

The report examines  options, with Alternative 2 designated as the agency’s preference for the “Proposed Rule.” Alternative 2 comprises acoustic elements designed to enhance vehicle detection, as well as low frequency requirements to enhance recognition of the sound as that of a motor vehicle. It establishes minimum sound requirements for EVs and HEVs at idle through 30 kilometers per hour (about 19 miles per hour), as well as in reverse.

Alternative 3, which also would be acceptable—but not preferred—contains acoustic elements for enhanced vehicle detection, but with several differences: No minimum sound is required at idle or above 20 km/h; no broadband low frequency sound is required; fewer one-third octave bands are specified; and the overall resulting minimum sound level is lower.

The NHTSA also qualitatively analyzed the potential environmental impacts of the action alternatives on wildlife. There are no established noise thresholds for wildlife because species vary widely in ability to tolerate noise and can exhibit very different responses to changes in noise levels. Wildlife is present in both non-urban and urban areas, and, therefore, has likely already adapted to current sound levels, allowing wildlife to continue to inhabit these areas in the presence of noise associated with these environments. Under either action alternative, sound levels would be very similar to the No Action Alternative, and overall vehicle sounds would be slightly lower than those of existing internal combustion engine vehicles; therefore, neither action alternative is likely to adversely impact wildlife

"Our proposal would allow manufacturers the flexibility to design different sounds for different makes and models while still providing an opportunity for pedestrians, bicyclists and the visually impaired to detect and recognize a vehicle and make a decision about whether it is safe to cross the street," said NHTSA Administrator David Strickland.

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 sent the proposal to the Federal Register on January 7. Upon publication, the public will have 60 days to submit comments on this NHTSA action.

Edited by Amanda Ciccatelli

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