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Sounds For Silent EVs, More Data, Same Result: Not Needed?

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A new study concludes that Prius repairs cost 8.4 percent more than repairs on non-hybrid economy cars.

A new study concludes that Prius repairs cost 8.4 percent more than repairs on non-hybrid economy cars.

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When we wrote about the debate over whether silent electric vehicles should have noise legislated into them, we obviously hit a nerve.

Now EV enthusiast Mark Larsen has added further data to his original analysis of 1994-2008 traffic death figures from the Fatality Reporting System maintained by the NHTSA.

He added a new analysis of injury data, not just fatalities. At speeds below the 15 miles per hour where electric-drive vehicles may be hard to hear, collisions between vehicles and pedestrians are far more likely to result in injury than death.

And, he also adjusted the injury and death statistics by vehicle-miles traveled, to produce accident rates that have been normalized over the same distance traveled--a better metric for comparison.

Pedestrian accidents and fatalities per billion vehicle miles traveled, 1992-2008, NHTSA data

Pedestrian accidents and fatalities per billion vehicle miles traveled, 1992-2008, NHTSA data

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And the result? Just the same: Larsen continues to question the need for mandated noise-making equipment to be added to electric and hybrid cars, calling it a solution in search of a problem that does not exist.

The data show that both pedestrian injuries and fatalities per billion vehicle miles traveled have fallen steadily since 1994, with a few blips here and there in the downward curve.

And the number of accidents involving blind pedestrians are "so extremely low that they are practically negligible," often just one or two per year. In 2006 and 2007, no fatalities occurred, and the sole injury recorded by the NHTSA was back in 1999.

Larsen also notes that throughout the 15 years, not a single blind person was recorded as killed or injured by a vehicle traveling at speeds less than 20 mph. In this case, it would appear that speed kills, but low speed neither kills nor injures.

Blind pedestrian accidents and fatalities per trillion vehicle miles traveled 1994-2008, NHTSA data

Blind pedestrian accidents and fatalities per trillion vehicle miles traveled 1994-2008, NHTSA data

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Nonetheless, as Larsen points out, "Recent lobbying efforts by the National Federation of the Blind have convinced the members of the U.S. Senate’s Commerce, Science, and Transportation Committee to include Amendment Sec. 109 in the proposed Motor [Vehicle] Safety Act [of] 2010."

In other words, if the amendment stands and the act passes, hybrids like the Toyota Prius and upcoming electric cars like the 2011 Nissan Leaf and Chevrolet Volt will have to emit noise under 20 mph without the driver having any control over it.

And that's where it stands today--data or no data.

Our thanks to EV advocate Chelsea Sexton, who passed along our thoughts on further analysis to Professor Larsen.

[Casteyanqui]

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Comments (2)
  1. Why not make all are cars and truck sound like harleys. We will all be deaf and can't here them anyway no matter what law congress passes.
     
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  2. I don't know if you've met or heard about Dr. Christopher Hogan who did one of the first papers measuring the hybrid hazard. It is in the official records of "www.regulations.gov" (search NHTSA-2008-0108) and dates from the summer 2008, the first NHTSA "Quiet Cars" hearing. More like a lynching, I was the only 'hybrid guy' there and my comments and suggestions are in the transcript.
     
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