Thursday, April 18, 2013

Road Safety and Driving Age

I've wanted to get my driver's license since I was at least five years old. My favorite toys were Matchbox cars, and I didn't go a day without creating miniature cities on my bedroom floor  My dad was in the Air Force, so we moved around a lot. I was born in Missouri, and from there we lived in places as diverse as Washington State and Guam. When I was 13, we moved to Minot Air Force Base, North Dakota, located near a small town called Minot (pop. 40,888 in 2010). I was very excited when I found out the driving age in North Dakota was 14. Permits could be obtained on a person's 14th birthday, and licenses could be administered six months later. I did get my permit when I was 14, but before I could get my license my dad retired from the military and we moved to Oregon. 

Compared to rules about driving age in North Dakota, ODOT's regulations seemed silly and intrusive. When I finally got my license on my 17th birthday, I wasn't allowed to drive at certain times or with other people under a certain age. It seemed to me that the roads weren't any safer here than they were in Minot. In fact, I witnessed a car accident for the first time in Salem. So this week's readings on safety reminded me of a question I've been wanting to ask: is road safety really impacted by driving age and/or graduated licensing programs?

The first graduated licensing program was introduced in 1996, but most states adopted them in the 2000s, with every state using some sort of graduated licensing system by 2011. In order to determine whether the amount of real fatalities was reduced by the introduction of these programs, I used data provided by the Census Bureau that tracks traffic fatalities by state from 1990 to 2009 (see below). I used passenger restrictions imposed on a driver with a graduated license as a measure of how "graduated" the licensing system is. Because advances in car safety, road design, and driver education have also made American roads less dangerous, I tried to account for that by determining the difference in reduction of fatality rates between seven different kinds of states.

They are as follows:
Group One, states who allow licensing at age 14 (no passenger restrictions): North Dakota, South Dakota
Group Two, states who allow licensing at age 15 (1 young passenger allowed): Idaho, Kansas, Montana, New Mexico
Group Three, states who allow licensing at age 15 (2 young passengers allowed): South Carolina
Group Four, states who allow licensing at age 16 (no passenger restrictions): Florida, Iowa, Louisiana, Mississippi
Group Five, states who allow licensing at age 16 (1 young passenger allowed): Alabama, Arizona, Arkansas, Delaware, Hawaii, Illinois, Kentucky, Michigan, Minnesota, Missouri, Nebraska, New Hampshire, New York, North Carolina, Ohio, Oklahoma, Pennsylvania, Rhode Island, Tennessee, Texas, Virginia, Wisconsin, Wyoming
Group Six, states who allow licensing at age 16 (no young passengers allowed): Alaska, California, Colorado, Connecticut, Georgia, Indiana, Maine, Maryland, Massachusetts, Nevada, Oregon, Utah, Vermont, Washington, West Virginia
Group Seven, states who allow licensing at age 17 (2 young passengers allowed): New Jersey

These groups are based on laws that are presently in place. As mentioned previously, I used Census data to determine if there was a correlation. Here's the chart:

Average fatality rates (per 100 million vehicle miles traveled) in 1990:
Group One: 2.05
Group Two: 2.51
Group Three: 2.80
Group Four: 2.55
Group Five: 2.02
Group Six: 2.06
Group Seven: 1.50

And in 2009, after the adoption of graduated licensing programs was near-universal:
Group One: 1.55
Group Two: 1.55
Group Three: 1.80
Group Four: 1.50
Group Five: 1.13
Group Six: 1.05
Group Seven: 0.80

Percent change:
Group One: -24.4%
Group Two: -38.2%
Group Three: -35.7%
Group Four: -41.2%
Group Five: -44.1%
Group Six: -49.0%
Group Seven: -46.6%

Based on these numbers, it would seem the naïve assumptions I made as a 17-year-old were incorrect. The more aggressive the graduated licensing program and higher the minimum driver age, the more dramatically fatality rates are driven down.

1 comment:

  1. Michael-

    This is an interesting post.

    Just to add some commentary to what you probably already used the variables 'age' and 'passenger restrictions' by state to formulate your data, and although it would have been laborious, there are a number of other variables at work that are probably just as important. Here are a few I am aware of: was a drivers education class taken? or required? (many states will allow one to become registered at 16 vs. 17 or 18 if one has been taken), in many mid west states one can be 'registered' at 14 but not for a car, truck, etc. only for what amounts to a moped (go to Iowa sometime and you will be amazed at the number of what look like 5 year-olds on mopeds blasting down the concrete roads out in the middle of nowhere (no-offense to anyone from Iowa - beautiful state, lovely corn fields)), many states also have varied restrictions on when a registered 16 year old can drive vs. that same driver at 17 or 18 (often the 16 year old can only drive during daylight hours), many states will also allow one to be registered at 14, 15 or 16 but they can only drive with an adult, lastly many states have special allowances for, among other things, farm related drivers.
    Another thing that would be interesting to look at and compare per-state is what the registration exam or process looks like and how has it changed over the years. I read a somewhat chilling piece years ago that said drivers tests and road tests had been greatly simplified and dumbed down over the past 30 years because too many people had been failing them. And finally, it would be interesting to compare these numbers with the other and of the spectrum - elderly drivers to see how they compare.


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