And safety doesn't just improve because people drive less in a tougher economic climate, although that's part of the picture. There is evidence that safety improves because recessionary times tend to take less-safe drivers off the road, which may help explain two remarkable trends in recent truck safety data.
In terms of both the number of fatalities and the rate of fatalities per mile, trucking showed record improvements from 2007 to 2008.
The number of people killed in large-truck crashes dropped by 12.3 percent to 4,229 in 2008, and the rate of truck and bus fatalities per 100 million miles dropped from .169 to .152, said Ralph Craft of the Federal Motor Carrier Safety Administration Analysis Division in a presentation last week. The 2008 fatal crash rate bests the agency's target not only for that year (.171) but for 2009 and 2010 as well, Craft noted.
The decline in fatalities, which was accompanied by an 11.2 percent drop in the number of fatal truck crashes, can be explained by the drop in vehicle miles traveled as a consequence of decreased economic activity. But the improvement in the rate of fatalities takes that mileage decline into account, so it requires a different explanation.
Craft believes that the agency's regulatory efforts have a lot to do with the improvement in the rate, even though it is hard to prove that statistically. But there also is statistical evidence that recession not only reduces the number of drivers but also culls out drivers who are less safe.
In a recession, the amount of rural and leisure driving go down more than urban and commuter driving, according to a study released last year by Michael Sivak, Head of Human Factors Division at the University of Michigan's Transportation Research Institute. Statistically, the rural and leisure group is less safe than the urban and commuter group.
"Recession affects certain groups more than others and it turns out that those that are more affected have a worse driving record to start with," Sivak said.
Another safety expert, Ron Knipling, senior research scientist at the Virginia Tech Transportation Institute, pointed out that recession also removes marginal trucking operations from the picture, which probably leads to better industry safety performance.
The safety improvement seen in the U.S. shows up all over the world, which makes it difficult to conclude that any particular regulation is driving the phenomenon, Sivak said. "We are skeptical to assign it to any particular intervention," he said. "The fact is, the (improvement) that we see here in the U.S. is more or less all over the world so what we do here is not likely to have an influence on the crash rate in England therefore it has to be something more fundamental."
Sivak also noted, as did Craft, that there is another recession-related factor: people drive slower. "An awful lot of crashes start with a little mistake," Craft said. "If you make that mistake when there are fewer vehicles on the road, you're less likely to have a crash."
The researchers agree that it is hard to statistically link safety gains with regulatory initiatives. "We believe that the safety programs we have in place help to reduce truck crashes," Craft said. "(But) it's very difficult to pin down the reasons for a lot of truck crashes. How much credit you give to our failing economy and how much credit you give to our efforts is very difficult to say."
Specific initiatives that Craft believes have made a difference include tougher requirements for new entrants into the business, and stronger enforcement. "We think we are doing a better job of putting existing companies out of service when they don't pay fines, or for other reasons. We're trying harder to make sure those companies don't come back."
Still, Craft offered a cautionary note. "After looking at truck crash data for 17 years the discouraging thing to me is that there's a lot of things we cannot regulate," he said. "We cannot make people pay attention when they drive. We can prohibit them from using cell phones, we can prohibit them from text messaging, but inattentiveness has been a major problem for years and years before the invention of cell phones and the invention of text messaging."
Craft said the agency is going to look in the data for any connections between safety and the hours of service rule. The agency is now reviewing the rule under an agreement between the Department of Transportation and a coalition of safety activist groups in which the coalition suspended its legal challenge of the rule pending completion of a new rule.
He said he is not aware of any studies that connect the hours rule to the better safety data, but the agency is going to probe the issue as part of the HOS revision. "Believe me, we are going to be looking at that."
BY THE NUMBERS
Here's a quick run-down on the key safety data Craft presented last week:
* Fatalities in highway crashes declined significantly during each of the three recessions in the past quarter-century. The current recession is the standard-setter: so far it has produced a dozen consecutive quarterly declines in fatalities, more than any of the other recessions. That count is likely to grow as more data come in.
* Beside the 12.3 percent drop in the number of people killed from 2007 to 2008, the number of large trucks involved in fatal crashes fell 12.2 percent to 4,068, and the number of fatal crashes involving at least one truck fell 11.2 percent. These declines probably continued in 2009, Craft said.
* The number of large truck occupant fatalities - mainly drivers - was down 15 percent.
* In 2008, large trucks were involved in 8 percent of fatal crashes, 2 percent of injury crashes and 4 percent of property damage only crashes.
* Fatalities in truck and automobile crashes have been generally falling: truck fatalities were 5,235 in 2004, and 4,229 in 2008; auto fatalities were 38,759 in 2004 and 32,479 in 2008. But motorcycle fatalities have moved in the opposite direction: from 4,103 in 2004 to 5,402 in 2008.
* Craft sees considerable safety gains from increased use of seat belts by truck drivers. He cited a survey by the National Highway Traffic Safety Administration showing seatbelt use increasing from 65 percent in 2007 to 72 percent in 2008, and tied it to a 15 percent drop in large truck occupant deaths between those years.
For more information on the webinar, go to http://www.fmcsa.dot.gov/facts-research/art-webinars-past.aspx.