Wednesday, May 28, 2008

Statistical Analysis of Alcohol-Related Driving Trends, 1982-2005

The U.S. National Highway Traffic Safety Administration has released a report (72-page PDF) that explores factors that influenced the historical alcohol-related driving trends from 1982 to 2005.
The number of fatal crashes that involved drivers who had been drinking at the time of the crash has decreased during the past two decades. The proportion of crash fatalities that are alcohol-related – that occurred in crashes where at least one of the drivers and/or non-occupants involved had a blood alcohol concentration (BAC) of .08 or above – decreased at a steady rate from 53 percent in 1982 to 34 percent in 1997. It leveled off for two years and then increased by 1 percent in 2000 and remained at that level for two more years before it decreased to 33 percent in 2005. The proportion of drivers involved in fatal crashes who had BAC of .08 or above decreased from 35 percent in 1982 to 20 percent in 1997 and leveled off thereafter, as shown in Figure 1.
The trend is good but the key is to decrease the number of drunk drivers as a percentage of total driver crashes.

In general, car crash deaths have remained somewhat constant for the past decade -- in the 43,000 per year range, although the number of drivers and miles driven have increased.

In a related story, according to a recent report from AAA, car accidents involving drivers 15 to 17 cost society more than $34 billion in medical expenses, property damage and related costs in 2006. This includes $9.8 billion related to fatal crashes, $20.5 billion connected with non-fatal crashes, and $4.1 billion for property damage losses.

I like this analysis because it looks at cost to society. The problem I have with NHTSA is they base all of their findings and funding on crash deaths; not cost to society. A fatal crash is cheaper to society than a non-fatal crash. Property damage being equal, medical expenses of an injured person is much greater than a person who dies in a crash, provided they die on the scene and not days or weeks later.

In defense of NHTSA, they have done a good job making cars safer. I just wish they'd consider total costs to society as a major metric, as the AAA Foundation for Traffic Safety has done.

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