IIHS - Improved Economy Increased Auto Accident Deaths - Small Cars Result In More Deaths

The risk of dying in a crash in a late-model vehicle has gone up slightly, as a stronger economy has led drivers to take to the road more often and in more dangerous ways. Meanwhile, a new study predicts traffic deaths will fall only slightly over the coming years, given current expectations for the economy.

The overall rate of driver deaths for 2014 models is 30 per million registered vehicle years, up from 28 for 2011 models (see "Saving lives: Improved vehicle designs bring down death rates," Jan. 29, 2015). The death rate for individual vehicles varies widely, from 0 for 11 vehicles to 104 per million registered vehicle years for the Hyundai Accent, a minicar.

The overall rate of driver deaths for 2014 models is 30 per million registered vehicle years, up from 28 for 2011 models. The death rate for individual vehicles varies widely, from 0 for 11 vehicles to 104 per million registered vehicle years for the Hyundai Accent, a minicar.

The last time IIHS calculated driver death rates, the overall rate had fallen by more than a third over three years. Researchers found that the drop was driven largely by improved vehicle designs and safety technology. Such improvements have continued, but the new results show that, by themselves, they won't be enough to eliminate traffic deaths.

"Vehicles continue to improve, performing better and better in crash tests," says David Zuby, IIHS executive vice president and chief research officer. "The latest driver death rates show there is a limit to how much these changes can accomplish without other kinds of efforts."

The new driver death rates are based on deaths that occurred during 2012-15. The increase in the overall driver death rate for 2014 models is likely connected to the increased number of fatalities toward the end of that period.

Falling unemployment, rising crash deaths

Road deaths have been trending downward since the early 1970s, with an especially large dip beginning in 2008. However, that changed in 2015, with deaths increasing 7 percent over the previous year. Preliminary data indicate the toll increased in 2016 as well. In the new study, Charles Farmer, IIHS vice president for research and statistical services, looked at what economic forecasts can tell us about traffic fatalities over the coming years.

An increase in traffic deaths is a predictable downside to an improving economy. As unemployment falls, both vehicle miles traveled and crash deaths increase (see "Stronger economy can be bad news for highway safety," Dec. 10, 2015). In a stronger economy, people tend to drive more. Riskier, discretionary driving — for example, going out to dinner or traveling for vacation — is affected by economic fluctuations even more than day-to-day commuting. Economic conditions also affect how fast people drive.

An increase in traffic deaths is a predictable downside to an improving economy. As unemployment falls, both vehicle miles traveled and crash deaths increase. In a stronger economy, people tend to drive more. Riskier, discretionary driving — for example, going out to dinner or traveling for vacation — is affected by economic fluctuations even more than day-to-day commuting. Economic conditions also affect how fast people drive.

To estimate how the annual death toll might change in the coming years, Farmer designed a statistical model based on the connection between traffic deaths and unemployment since 1990. The model also includes calendar year, thereby accounting for safer vehicle designs and other highway safety improvements that have taken hold over time.

Farmer found that a decline in the unemployment rate from 6 percent to 5 percent is associated with a 2 percent increase in vehicle miles traveled. That jump in exposure leads to an equivalent 2 percent jump in fatalities. However, after accounting for the change in miles traveled, the decline in the unemployment rate is associated with an additional 2 percent increase in road deaths. In other words, only half of the effect of an improved economy on traffic deaths is due to increased driving.   

Given the U.S. Bureau of Labor Statistics' forecast of a 1.7 percent annual reduction in unemployment from 2014 to 2024, he predicts that the recent increase in deaths will have peaked in 2016 and estimates there will be approximately 34,400 traffic deaths in 2024, compared with 35,092 in 2015.

If unemployment doesn't change as predicted but remains steady at the 2016 rate of 4.9 percent, there will be 33,600 traffic deaths, Farmer estimates. In either case, the projected
number of crash deaths for 2024 is still higher than the 32,744 deaths seen in 2014.

The recent surge in crash avoidance technologies, along with the development of autonomous vehicles that in theory could eliminate all crashes, has the potential to bring down crash rates. However, it will take decades before such technologies are present in all new vehicles. Vehicles with varying degrees of automation will be sharing the road with conventional vehicles for some time (see Status Report special issue: autonomous vehicles, Nov. 10, 2016).

The recent surge in crash avoidance technologies, along with the development of autonomous vehicles that in theory could eliminate all crashes, has the potential to bring down crash rates. However, it will take decades before such technologies are present in all new vehicles. Vehicles with varying degrees of automation will be sharing the road with conventional vehicles for some time.

"Improvements in vehicle technology are important, but we also need to address old problems such as speeding and driving while impaired," Farmer points out.

Tiny vehicles, high death rates

As in the past, the driver death rates show that the smallest vehicles are the most dangerous ones. Among the 10 vehicles with the highest rates, five are minicars and three are small cars. These vehicles don't protect occupants as well as larger ones, so their presence at the top of the "worst" list isn't surprising.

Among vehicle categories, 4-door minicars have the highest overall death rate of 87, while 4-wheel-drive large luxury SUVs have the lowest with 6.

Despite the increase in the overall rate, the worst vehicles actually saw some improvement. The 2014 Hyundai Accent's death rate of 104 compares with 120 for the 2011 Accent. The worst vehicle among the 2011 models was the Kia Rio with a rate of 149. The 2014 Rio's death rate is 102. Both models were redesigned in 2012, and their lower death rates may reflect the better crash-test performance of the newer designs.

IIHS has been publishing death rates per registered vehicle year by make and model since 1989 (see Status Report special issue: death rates, Nov. 25, 1989). The rates include only driver deaths because all vehicles on the road have drivers, while not all of them have passengers or the same number of passengers. Fatality counts are taken from the federal Fatality Analysis Reporting System, and registration data are from IHS Automotive. The calculated rates are adjusted for driver age and gender.

IIHS has been publishing death rates per registered vehicle year by make and model since 1989. The rates include only driver deaths because all vehicles on the road have drivers, while not all of them have passengers or the same number of passengers. Fatality counts are taken from the federal Fatality Analysis Reporting System, and registration data are from IHS Automotive.  The calculated rates are adjusted for driver age and gender.

Although the numbers reflect 2014 models, data from earlier models as far back as 2011 are included if the vehicles weren't substantially redesigned before 2014. Including older, equivalent vehicles increases the exposure and thus the reliability of the results. To be included, a vehicle must have had at least 100,000 registered vehicle years of exposure during 2012-15 or at least 20 deaths.