This photo of a car elevated in a brick wall North Avenue and Kedzie Avenue by Katherine Hodges is not related to the story below.
A comment was left on EveryBlock, in response to a crash at Lincoln and Fullerton, “What a shock, alcohol was involved” (here’s a newspaper’s report). I presume that many other people think alcohol is typically a cause or factor in automobile crashes. I looked at the data to know if it’s true.
From 2007 to 2010, there were 394,651 reported crashes. Of those, responding police officers marked on the crash reports (SR-1050) that being under the influence of alcohol or drugs was a primary or second cause in only 3,647 crashes, or 0.924%. However, this does not tell the full story. That “cause code” (#8) is to be used when an arrest is made. When an arrest is not made, officers are to use “had been drinking” (#19), from which the data shows 1,030 crashes. Adding them together, you have 4,677 crashes. In other words, alcohol is a contributing primary or secondary cause in 1.185% of crashes.
What is the most frequent cause? The top five causes (combining primary and secondary), excluding “NA” (the most frequent), are:
- Unable to Determine – 168,551 crashes
- Following Too Closely – 46,271
- Failing to Yield Right of Way – 46,112
- Failing to Reduce Speed to Avoid Crash – 36,991
- Driving Skills/Knowledge/Experience – 29,325
Under influence of alcohol or drugs is #16, and Had been drinking is #24.
Again, we’re not done with the story as people can still be drinking and driving without it being listed as a “primary” or “secondary” cause of the crash. I’m just less likely to be sure that it was a factor in the crash (and I’m assuming that all police officers responding to crashes have been trained well, equally, and are applying their training accurately and consistently – not likely the case).
In the data of 394,651 crashes, there were 1,041,378 drivers. The top “driver’s apparent condition” attributes are:
- Normal – 80,9283 drivers
- Other/unknown – 20,9015
- Impaired with alcohol – 12,445
- Had been drinking – 3,277 (this attribute has the same name as the one applied to crashes but this one applies to one of the drivers in the crash and may not related to the Crash Cause)
- Asleep/fainted – 2,310
Impaired with drugs is #8, attributed to 1,348 drivers.
Anti-drunk driving campaigns
If the findings tempt you to feel that we should be spending less attention on safety campaigns to reduce the frequency of driving while drunk, hold on. I’m not ready to make the judgment about the level of attention being paid to drunk driving. I don’t know the trend of drunk driving. Has it gone down? Are the strategies we have in place reducing the proliferance of drunk driving? If that’s true, we should probably keep them going.
But it’s clear that there are more kinds of crash causes than are being addressed. Look at the fifth most frequently cited cause, Driving Skills/Knowledge/Experience. Perhaps that tells us we should expend more resources on shoring up high school driver’s ed programs, instituting mobility education, or having driver’s ed students be in a probationary period longer (the Chicago Tribune had an excellent investigation into this in 2006 that helped lead to a graduated license program in Illinois).
The next step
It should be a shock that alcohol was involved: its presence or attributable cause in car crashes is rare. But this does not discount that crashes having alcohol present may be more severe than crashes without alcohol. That’s the next step in this data analysis. I will also be looking into alcohol presence in crashes with people who were walking or biking, or riding or driving buses.
If you are reading “Traffic” with me, then you probably understand that a driver’s own behavior is only one (measly) factor in the quality of their driving. Other factors include humans’ inability to process what we’re seeing at the speeds we’re seeing them, or think we’re seeing them (meaning we pass when we shouldn’t); the design of roadways; and a lack of cooperation when changing lanes. And that’s just in the first 90 pages of the book.
Where can different road designs play into reducing the number of crashes? And how we can address speeding (or that humans do a terrible job of estimating their own and others’ speeds)?
Note: I know I write a lot about driving on Grid Chicago, and that our mission is to promote active and sustainable transportation. The overwhelming presence of cars on the road, and the injuries this leads to, is a major barrier to progressing our mission. As long as people using active and sustainable transportation continue to receive preventable injuries in crashes with automobiles, I will keep writing about this.
If you would like to visualize this information, I’d be happy to help you and publish the results. Contact me steven @ gridchicago.com.
(1) From the Chicago Sun-Times: “The [Illinois] department [of Transportation] released data showing a steady decline in such deaths in Illinois from 2006 through 2010. In 2006, there were 446 deaths related to impaired driving on Illinois roadways. By 2010, there were 298 deaths in crashes involving alcohol.”
I’ll look into the rate for the City of Chicago to see what happened.
(2) Jason noted in the comments the extreme hit and run rate in Chicago. Gabe Klein noted this in one or two interviews (and this isn’t the first time we’ve written about it). What’s the rate? From 2007 to 2010, 28.93% of crashes were reported by the police as “hit and run”. Here is a breakdown for each of those years:
- 2007 – 32,656 (27.18% of 120,163 crashes)
- 2008 – 29,994 (26.85% of 111,701)
- 2009 – 26,140 (31.89% of 81,982)
- 2010 – 25,370 (31.40% of 80,805)
Updated December 21 to add data about hit and run crashes; December 24 to add Sun-Times story about decreasing deaths statewide.