Motorcycles and the Statistics of Death*

*Somerset, PA  Daily American
April 16, 2011
as "Motorcycles and statistics"

Copyright © 2011 by Ralph Couey

Motorcycle riding season is nearly upon us, and naturally I am eagerly awaiting the nexus of meteorological conditions conducive to safe riding.

My colleagues, out of their concern for my safety, deposited the latest edition of the Journal of Forensic Science on my desk.  You might characterize this publication as the pinup magazine for Coroners.  Three articles were bookmarked.  One was entitled, “Massive Lesions Owing to Motorcyclist Impact Against Guardrail Posts,” a study of two accident victims who, after losing control of their rides, slid across the road and slammed into the posts supporting the guardrails, cutting one of the riders literally in half.  I’ll spare you the gory details, but I have to admit the pictures were kinda cool.  Another article, called, “Traumatic Testicular Displacement in Motorcycle Drivers” went into excruciating detail (including some not-so-cool pictures) about the fate of the family jewels during the trauma of frontal collisions. 

Touched as I was over their apparent concern, I read the articles over and set them aside.

The third one was the most interesting.  “Death by Motorcycle:  Background, Behavioral, and Situational Correlates of Fatal Motorcycle Collisions.”  This was an impressive statistical study done by Dr. Samuel Nunn, Professor of the School of Public and Environmental Affairs and Director of the Center for Criminal Justice Research, part of the Indiana University-Purdue University of Indianapolis. 

Like many professional journal articles, this one needed to be read with a dictionary and thesaurus close at hand.  While statistics is still a big mystery to me, there were enough plain-language findings in the paper to get my attention.

Some of the findings I already knew, like the fact that as of 2007, “motorcycles were 27.5 times as likely to be part of a fatal collision than passenger cars.”  Also, “the mechanism of injury resulting in death usually comes from severe blunt force trauma.”  These were obvious facts to anyone who rides.  But Dr. Nunn explored further into what he called “the train of morbid events,” or the sequence that led to a rider’s death.

He came up with three fundamental agents of death:

1.      Collision with another motor vehicle

2.      Collision with another stationary or moving non-vehicular object

3.      Some other harmful action by motorcyclists

The data for this study came from Police crash reports of 18,225 motorcycle operators in the state of Indiana who were involved in collisions between 2003 and 2008, including those who died within 30 days of their accident.  In analyzing those reports, Dr. Nunn developed these dominant factors:

·         87% of victims were men

·         50% of fatalities occurred on Friday, Saturday, or Sunday

·         60% of deaths occurred in rural areas.

·         66% of fatalities involved helmetless riders, where that factor could be identified.

Over half of the fatal crashes (51.5%) were collisions with other motor vehicles.  Another 28.4% of cases involved the rider losing control of the bike.  Those two factors accounted for over 80% of deaths.

Another sobering finding was that drug use increased the odds of death by almost 30%.  Dr. Nunn stated, “The presence of drugs contributed significantly to serious injury,” something that all should be aware of. Alcohol was next at 11.1%.  For non-vehicular collisions, trees were the most deadly point of impact.  For vehicular collisions, crossing the centerline was another significant cause. 

Higher speeds increased the odds of death, which led to a surprising finding that lower odds of fatalities occurred on wet roads because riders generally ride at slower speeds in the rain.  Note that this study didn’t explore causes of accidents, just fatalities.  In conditions where the weather was not clear, as in fog, the odds of dying were nearly doubled.

Perhaps the most obvious finding was that higher fatality rates occurred in darkness, on curves, and when the rider was engaged in “errant or risky driving.”

Dr. Nunn stated that the average age of riders who perished was almost 2 years older than those who survived, but that finding was inconsistent with studies done in other countries.  Still, according to his findings, the odds of dying in a motorcycle accident increase by about 1.5% for each year of aging.

Darkness was significant in several ways.  Riders were more likely to engage in risky riding habits in the dark.  Also, they were more likely to have been drinking prior to riding.  Darkness reduces distance vision, making it more difficult for riders to react in time to hazards.

One of the gaps in this study was the number of deer strikes.  I know a lot of riders cross swords, or antlers as it were, with Bambi and his brothers and sisters, particularly between dusk and dawn.  I would have expected some discussion of this hazard, especially in data from Indiana.

Dr. Nunn states emphatically, “Helmet use drives down the odds of death.”  This finding, added to the recent study showing that modern helmets also helped to decrease cervical spinal injury, point to the obvious prudence in wearing the brain bucket.  He concedes, however, that in some accident scenarios, the combination of other factors, i.e. excessive speed, risky riding habits, trees, bridge abutments, canceled the advantage gained.  The sad fact is that in some cases, the forces involved in a collision will kill you regardless of safety gear, or the lack thereof.

Adding all these factors together, Dr. Nunn concluded that the most likely scenario of death involves men, 21- to 44-years old riding in the dark between Friday and Monday, with a reasonable suspicion that those riders were chemically impaired.

Statistics can be cold, and certainly don’t express the tragedy of human death.  But this paper goes a long way towards identifying those criteria that place us at the highest risk.

And forewarned is always forearmed.