Saturday, June 13, 2009

How Dangerous are Motorcycles?

I happened to look at motor vehicle accident statistics the other day and noticed that the NHTSA now gives stats on the number of fatalities per 100 million passenger miles for motor vehicles and motorcycles. I was interested, since I looked for these numbers back around 1990 and couldn't find them and attempted to compute my own figures.

The reason I was doing this, is I wanted to calculate how much more dangerous is was to ride a motorcycle than to drive a car. A little Googling and I found a copy of the numbers I posted in rec.autos.driving in 95. The obvious problem with what I did then was that I didn't have any conversion for vehicle miles to passengers miles and I just assumed 1 person per car. I looked around and found a number in commuting statistics of 1.3 people per car and plugged that in.

Here are my numbers and the NHTSA stats:


 Fatality Rate Per 100 Million Vehicle Miles Traveled
Year Motorcycles Automobiles Ratio
83 46.18 1.77 26
84 49.84 1.77 28
85 47.79 1.70 28
86 44.79 1.72 26
87 38.37 1.65 23




Year Motorcycles Automobiles Ratio
1997 20.99 1.64 13
1998 22.31 1.58 14
1999 23.46 1.55 15
2000 27.67 1.53 18
2001 33.17 1.51 22
2002 34.23 1.51 23
2003 38.78 1.48 26
2004 39.79 1.44 28
2005 43.77 1.46 30
2006 39.00 1.42 27

The first thing to notice is that the motor vehicle safety record consistently improved from 1983 to 2006. The fatality rate dropped by 20% during that period.

The motorcycle results aren't so happy. The results from 87 to 97 dropped from 38 to 21, but then climbed back up to 39 per 100 million miles in 2006. This means that by 2006 you were 27 times as likely to be killed driving a motorcycle as a motor vehicle on a mile per mile basis.

Some people would protest that comparing motorcycles to all vehicles is inappropriate and that subcompact cars would be the closest equivalent. The NHTSA doesn't break their passenger miles data by motor vehicle type, but they do have rates per 100,000 registered vehicles. All motor vehicles are 15 per 100,000, while subcompacts are 17 per 100,000. That would reduce the danger ratio above from 27 to 24.

Nothing I have written above should be inferred to mean that I think motorcycles should be outlawed or even to require helmets. I tend to be of a libertarian persuasion and think people should be left alone if they aren't bothering anyone else. Besides hospitals always need more organ donors.

If any of my motorcycling friends should read this and wondering if I'm implying that they are stupid and/or insane: the answer is yes.

References:

Re: safety in cars, speed limits, and motorcycles
http://www.ibiblio.org/rdu/usenet-arc/sub00073/msg00001.html

NHTSA Traffic Safety Facts 2007 Data: Motorcycles
http://www-nrd.nhtsa.dot.gov/Pubs/810990.PDF

NHTSA Traffic Safety Facts 2007 Data: Overview
http://www-nrd.nhtsa.dot.gov/Pubs/810993.PDF

NHTSA Traffic Safety Facts Research Note January 2006
http://www-nrd.nhtsa.dot.gov/Pubs/809979.PDF
Posted by at 11:38 AM
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4 comments:

  1. The big difference between cars and motorcycles is obvious. When on a motorcycle you don't have 3,000 lbs of steel surrounding you in the time of impact. It's just your body against the road. The fatality risks is amplified at that point.
    ReplyDelete
  2. The thing is we're comparing motorcycling with something REALLY safe (driving).

    Read the stats, no really read them... 39 per hundred million miles or 1 per 2.5 million miles. As an above average milage rider (about 10,000 miles per year), my risk of death actually equates to once every 256 years, my risk of death just by being alive is greater than that!

    Life is just dangerous, but what's worse, living life to the full (with risk) or waisting your life coasting through a long and boring existence on the way to death.
    ReplyDelete
  3. Yes but one in 256 years is one in ten over 25 years. Or 1 in 100 over 2.5 years. That's scary!
    ReplyDelete
  4. "my risk of death actually equates to once every 256 years"

    Yup. On average you need 256 of biking to die in a bike crash. Lets examine the implications:

    Suppose we have 7 friends who ride a bike.

    Suppose they are bikers since they are 20yo until they are 60yo. 40 years of riding.

    Well: Statistically one of them is going to die in a bike accident.

    In a group of 14 bikers 2 of them would die in a bike accident. How reassuring...
    ReplyDelete

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