Roger’s post on car crashes a few weeks back got me to thinking: what are the local car crash trends looking like, in an era of expensive gas?
And as it turns out, the trends are looking good!! The state of Washington recently released fatality statistics for 2008, and their figures show a sharp dip in fatality rates in the past few years. As the chart to the right shows, crash fatality rates have been on the decline for decades; but the decline has actually accelerated in the past few years. (Data are here, in table E8, in case you’re interested; and they’re “age adjusted” to compare apples to apples each year.)
The same thing is happening in British Columbia, by the way. The data I’ve found (click here for an Excel spreadsheet) aren’t directly comparable to Washington’s, and only go back through 1986 and stop in 2007. But the province has experienced a similar “crash” in car crash risk.
This is all good news: car crashes have long been the leading killer of people under 40 in this part of the world, and any dip is welcome. Of course, the time we spend behind the wheel remains some of the riskiest we spend all day—and our total risk goes up for every mile we drive. But the fact that cars are still dangerous shouldn’t keep us from celebrating a decline in motor vehicle fatalities.
As far as I can tell, there are at least two separate trends in play here. First, driving is getting safer. And second—measured per person, at least—we’re driving less.
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Let’s look first at car safety. Over the years, federal safety standards, coupled with insurance industry pressure, have steadily made our cars safer. Take a look, for example, at this video of a 2009 Chevy Malibu demolishing a 1959 Chevy Bel Air.
Note that the Bel Air is actually heavier than the Malibu. Not by a lot—but still, in this case the lighter car wins. This shouldn’t all that surprising, really. As this report (somewhat dated, but still interesting) shows, car design is a better determinant of vehicle safety than weight; heavy SUVs, for example, are no safer for their occupants than a mid-sized sedan.
For me, the important thing to remember about safety improvements is that the auto industry fought tooth and nail against many safety advances, often claiming that government safety regulations would put them out of business, or restrict consumer choice. So when you hear the same sort of crocodile tears from the auto industry about efforts to boost fuel economy, to levy carbon taxes, or to institute a carbon cap and trade system, you’ll at least know that there’s a long history of that kind of silliness.
Second, let’s look at driving trends. The chart to the left shows that in Washington state, per capita vehicle travel fell by about 8 percent between the middle of 2005 and the end of 2008. During that stretch, vehicle fatalities in the state fell by about 20 percent. Although it might seem a stretch to attribute a 20 percent decline in fatalities to an 8 percent drop in per-capita driving, it’s at least somewhat plausible. As Todd Litman of the Victoria Transport Policy Institute points out, crash risk tends to accrue by the mile, and because most traffic crashes involve more than one vehicle, every 1% dip in VMT should result in a nearly 2% dip in car crashes.
There was a lot of wailing and gnashing of teeth about skyrocketing gas prices a few years back. That’s understandable: many families felt like they didn’t have a choice about how much they drove, and rising gas prices really put a squeeze on many household budgets. But it’s important to remember that, as unpleasant as high gas prices seem, they’ve got a silver lining: higher gas prices means less driving, and less driving means fewer traffic deaths. And saving lives has an economic upside; the National Safety Council estimates that each traffic fatality corresponds to about $5.96 milion in costs. All told, there were 149 fewer traffic deaths in the state 2008 than in 2005—the equivalent of a $900 million boost to Washington’s economy in 2008 alone.
So what will happen next? Will crash in car crashes continue? Or if gas prices stay low, or if the economy picks up, will we see an uptick in both driving and crashes? I’ve got no predictions, really—just a hope that the traffic fatality rate keeps going down, regardless of what happens to driving trends.
What shockingly shoddy journalism. Not unusual these days, of course, but really. The data for overall car accident rates and injury (as opposed to fatality) rates are readily available. These will quickly give you a better picture of how much of the fatality rate improvement should be attributed to vehicle design, and with a phone call or two to your Doctor contacts, you could also get a decent estimate of how much can be attributed to improvements in medical practices (which you haven’t so much as considered in your opinion piece).Why publish speculation when a little bit of easy legwork might give you actual answers?
Robotslave-Well, here’s what I meant when I wrote “As far as I can tell, there are at least two separate trends in play here.”** Total reported collisions in Washington state show a flat or rising trend from 2000 through 2005, followed by a sharp decline from 2006 through 2008—which correlates with both VMT and traffic fatality trends, and is consistent with independent findings that traffic risk accrues roughly per mile driven. However, total collisions are not tracked as comprehensively and reliably as are traffic fatalities. I could only find comprehensive collision data for Washington state from 2002 to the present, for example; data for collisions on state highways are available from 2000 through 2002, and also in 1996 (in an inconsistent format). Also, only collisions reported to the police are tallied, so minor collisions may not be covered—which adds some uncertainty to the data.So AS FAR AS I CAN TELL, given the limitations in the data, the very recent rapid decline in traffic fatality rates is related to declines in VMT.** Both the number of fatalities and the number of injuries per reported collision have gone down over time. I feel justified in saying that the well-documented improvements in car safety have contributed to a decline in injuries and fatalities per collision, particularly when viewed from 1980 through the present. However, the trends may also result from changes in roads, driving conditions, congestion, traffic enforcement, driver skill, or drunk driving rates, that make each collision less likely to result in a fatality. Teasing out the causal relationships is, well, the work of a masters’ thesis or PhD dissertation, not an observational blog post.So, AS FAR AS I CAN TELL, improvements in car safety are a contributing factor in the declining number of injuries and fatalities per collision.** If improved emergency medical care were a significant factor in the decline in traffic fatalities, then I’d think we’d see a significant decrease in the number of traffic fatalities per traffic injury—as previously fatal collisions were converted into merely injurious ones. But instead, from 2000 to the present, fatalities per reported injury have shown no consistent trend. To me, this suggests, but does not prove, that changes medical care been a a fairly minor factor in the 2000-2008 declines in traffic fatalities. Then again, injury data are spottier than for traffic deaths—in part because the definition of “injury” can vary, and Washington’s recently shifted its definition of injuries, which makes the numbers difficult to interpret.So I stand by my statement: “As far as I can tell, there are at least two separate trends in play here.” Cars are safer, and we’re driving less.By the way, this is a blog—a mixture of fact and opinion. There’s plenty of other stuff on the web to read; please feel free to find something that you like.
“heavy SUVs, for example, are no safer for their occupants than a mid-sized sedan”Not true. Look at the data from the IIHS. It’s clear that heavier vehicles are safer for occupants than lighter vehicles.
Mark-I respectfully disagree. The work of Wenzel & Ross (see http://eetd.lbl.gov/ea/teepa/pub.html for a list of their publications) has convinced me that vehicle mass is a poor predictor of occupant safety.