Study Shows That Higher Speed Limits Equate to More Highway Deaths
Over the past few decades, many states have raised the speed limits on their highways. The good news is that drivers can reach their destinations faster. The bad news is that more of them are never reaching their destinations at all. A recent study shows that higher speed limits have led to increased numbers of fatal accidents.
In 1973, amid concerns about fuel shortages, Congress passed a law that required states to set their highway speed limits at 55 mph or lose federal highway funds. They all adopted the 55 mph limit. A side effect of the law was a reduction in death rates on the roads.
By 1987, fuel supplies had grown, reducing the impetus for conservation efforts. Congress amended the law, permitting states to raise the speed limit to 65 mph on rural highways. By 1995, the law had been repealed entirely. Supporters of repeal called it a recognition of the reality that few people were obeying the 55 mph limit. However, subsequent studies showed that travel speeds increased after the repeal.
Some states have gone far beyond the old 55 mph limit. Six states now have 80 mph limits; Texas has an 85 mph limit on some roads.
A recent study by the Insurance Institute for Highway Safety examined the effects of all speed limit increases between 1993 and 2013 in 41 states. Researchers broke down data on the number of fatalities per billion miles traveled by state and road type (urban, rural, etc.). They further controlled for other factors that influence fatality rates, such as unemployment rates, number of potential drivers between ages 16 and 24, and alcohol consumption per capita.
The findings: Fatalities increased by four percent for every five mph increase in speed limits. The increase was even higher on interstate highways and freeways - eight percent.
The researchers compared the actual fatality rates to what they would have been if each state had left its speed limit unchanged since 1993. They estimated 33,000 additional people have died because of the higher speed limits. In 2013 alone, the additional fatalities were 1,900. By comparison, the number of people who died on the Titanic was slightly more than 1,500.
The researchers believe the 33,000 figure understates the actual number. They looked only at the increases on rural highways, but some states also raised the limit on urban roads. Others raised the limit on one section of a highway and later raised it for other sections, actions the study did not examine. Also, since the study period ended five states have raised their speed limits above 75 and others have gone from 65 to 70.
It appears that American drivers' need for speed is shortening their lives. Beyond the tragedy of lives ended early, this trend imposes additional costs - higher taxes to pay for more emergency services, increased medical expenses, and hikes in auto insurance premiums. Whether the benefits of higher limits justifies these costs is something lawmakers in each state must decide.
March 26, 2017
by Scott Ligouri
Founder + Managing Partner