[Quietcars] Preliminary 2007 Accident Analysis

[Robert Wilson]

Hi,
I'm just sharing the latest information about the new, 2010 Prius and analysis of the 2007 Fatality Accident Reporting System (FARS). Both relate directly to the public debate on H.R. 734 and S. 841.
The 2010 Prius incorporates crushable, impact absorbing structures in the bumper, hood and quarter panels to reduce injury in an impact. These features are described in the New Car Features document "2010-Prius-NCF-Ext-Body-Details:"
"(d) Lessening Pedestrian Injury (1) An energy absorber is provided at the front of the front bumper reinforcement to dampen the impact to the legs in the event of a collision with a pedestrian. (2) A longitudinal ribbed structure is adopted for the inner hood to cushion impact. (3) The space between the hood panel and the hood lock striker has been formed into a crushable structure so that the hood sub-assembly can collapse easily during a collision. (4) An impact absorbing bracket is used for the mounting portion of the front fender panel to absorb impact energy to the head of the pedestrian in a collision, thus dampening the impact to the head. (5) The back of the hood and the cowl use an open section structure that collapses easily in an impact from the top, thus reducing the impact to and head injuries sustained by a pedestrian in an accident."
The Prius has pedestrian accidents and making vehicles safer for pedestrians is the responsible thing every manufacturer should do to reduce deaths and injuries. But HR 734 and S 841 do not address this practical approach, a way of reducing the 4,700 pedestrian deaths that occur each year. It only addresses one group of vehicles and simply declares them to be a hazard in the absence of supporting accident data.
Recently I started an independent analysis of the National Highway Traffic Safety Administration (NHTSA) Fatal Accident Reporting System (FARS) data. The FARS web page reporting systems are difficult to use but the raw database files can be downloaded for analysis. Dr. Christopher Hogan had previously used the same NHTSA files to analyze the 2002-2006 FARS data and could find no evidence of a Prius-pedestrian hazard. But the 2007 data became available later so I decided to take another look. Now this is a 'back of the envelope" analysis using the most conservative (worst case for Prius) and I'm finding:
~554,324,000 miles per pedestrian death for all USA vehicles (NHTSA 2007 report)~1,023,116,000 miles per pedestrian death for all USA Prius (Analysis of 2007 FARS data)
For worst case assumptions, I used:
 - 5% of all Prius leave the USA fleet every year leaving 477,000 Prius in 2007 from the first year of sales through 2007. - 6 Prius-pedestrian accidents in 2007, we counted all pedestrians as fatalities, 7, which is the worst case. The actual number of pedestrian fatalities could be less.
Each Prius is about half as likely to be involved in a fatal pedestrian accident than any ordinary USA vehicle. A more precise and detailed analysis of the 2007 accident data may shift the precision but not the results. Prius on USA streets in 2007, without HR 734 and S 841, means all pedestrians are safer than with ordinary vehicles.
I found six pedestrian-Prius accidents in the 2007 data:
01/05/2007 - CA 45 mph speed limit01/24/2007 - CA 40 mph speed limit01/26/2007 - FL 45 mph speed limit09/12/2007 - FL (*) 65 mph speed limit10/18/2007 - TX 60 mph speed limit10/21/2007 - AZ 50 mph speed limit
* - this accident involved two pedestrians who tried to race across an Interstate highway in the rain in front of 2006 Prius. At highway speeds, the Prius driver could not avoid hitting them and they were thrown into the path of other vehicles. No driver was charged because these pedestrians ran into highway traffic. No amount of sound could have prevented this accident. We have the Prius driver's report and news report available on the net.
The accident data maps the real world, Prius-pedestrian accident risk. If you would like copies of the data or just the details on how to get the data, feel free to ask. Everything is in the public domain.
Rosenblum reports that the Prius is more difficult to detect by sound alone at speeds under 30 mph. But his worst case ratio of this single element doesn't scale to the real-world accident numbers. If anything, the real accident data using the harshest assumptions against the Prius suggests they are about two times safer than ordinary USA vehicles. 
Bob Wilson625k Inc
 
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