Sponsors of the studies are cautious about drawing hard conclusions about what's causing fatalities and fatality rates to decline. They don't want to confuse coincidence with cause and effect. But it could be that years of efforts to improve the safety of vehicles, highways and drivers – using a mix of regulation, education and what amounts to marketing – are starting to pay off.
The National Highway Traffic Safety Administration's preliminary review of 2008 crash data concluded that during the first 10 months of 2008, traffic deaths fell by about 10% to 31,110 people lost. The number of deaths per 100 million vehicle miles traveled declined to 1.28 during the January-October period from 1.37 in the same 10 month period of 2007.
A separate study by the Governors Highway Safety Association (GHSA) found that highway deaths declined an average of 10.7% last year in 40 states and the District of Columbia. The GHSA analysis also concluded that in many states, deaths fell at a faster rate than vehicle miles traveled.
Here a few reasons for the decline in fatalities:
The economic slump and the gas price shock may have helped, by keeping people off the road and encouraging them to slow down. The GHSA study notes that several states reported that drivers were slowing down, with average speeds in Oregon dropping by 1 mile per hour.
People driving slower were almost certainly getting better mileage. A study by the General Accounting Office, conducted at the request of then Sen. John Warner of Virginia, concluded that most cars and trucks get their best mileage at speeds between 30 and 60 miles per hour. A 1994 Chevy pickup traveling at a steady 45 miles per hour could get 27.3 miles per gallon, the report found. A 2005 Focus traveling at a steady 40 miles per hour could get 45 miles to the gallon.
Going slower also gives motorists a better shot at avoiding or surviving collisions.
We may also be getting the benefit of what is now nearly 20 years during which the auto industry has increasingly taken the view that safety is something they can sell – not just an annoying regulatory mandate.
Cars are safer in part because the federal government during the 1970s and 1980s forced the industry to adopt technologies – including seat belts and airbags – that it had resisted at first.
More recently, auto makers have been going beyond what the law requires, because that is increasingly what consumers demand. The increasing use of stability controls and anti-rollover systems is an example. Electronic stability controls will be mandated on new vehicles by 2012, but many new vehicles have this technology today.
The number of vehicles in all classes that score poorly in crash tests conducted by the Insurance Institute for Highway Safety (IIHS) or the National Highway Traffic Safety Administration (NHTSA) has declined steadily, coinciding with the rising ease with which consumers can get access to information about how well or poorly cars fare in such tests.
The NHTSA has worked to make the online presentation of its star ratings for crash tests more accessible and meaningful over the years.
The IIHS has been even more aggressive in using the power of shame to push car makers to beef up their designs for crash-worthiness, offering its hair-raising crash test videos to television networks and posting its scores and its scolding words for laggards on its Web site.
The Insurance Institute recently crash tested a group of small cars and found that 11 of 21 earned good ratings for side impact protection – compared to just 3 of 19 small car models tested in 2006. In any vehicle, side-on crashes can be the deadliest, because there's so little metal between the occupant and the oncoming vehicle.
Changing public attitudes make a difference, too. The campaign to make driving while intoxicated not just a serious crime, but socially unacceptable, has coincided with a drop in alcohol related highway deaths – although thousands still die in crashes involving people who've been drinking.
The effort to get more motorists to wear seatbelts appears to have reached a tipping point as well. The NHTSA says 83% of motorists wore their belts, the highest rate in history. "Click it or Ticket" laws seem to be working – whether your view is that fining people who won't buckle up is an intrusive way for governments to raise revenue, or a necessary policy to overcome the resistance of negligent people who are putting themselves and their families at risk.
Finally, look for safety advocates to use the good news of falling highway death rates to make a case for more spending to add safety improvements to highways, Ms. Harsha says. Missouri, for example, has put median barriers – essentially cable fences – down the centers of its major interstates to prevent vehicles from skidding into oncoming lanes.
No one factor explains the huge toll of highway deaths in America, and no one factor will likely drop the death toll to a point where it's no longer a significant issue. But the recent trends do suggest that persistent efforts are slowly and steadily yielding results.