The Insurance Institute for Highway Safety reports more motorists are speeding and choosing faster cars, resulting in significantly more deaths per million vehicle miles.
Higher speeds on rural interstates are responsible for a 35 percent increase in death rates, according to a recent report from the institute, a research and communications organization funded by auto insurers.
The report notes research by the Land Transport Safety Authority of New Zealand. The authority examined U.S. rural interstate deaths following the 1995 repeal of the national maximum speed limit.
States that increased speed limits to 75 mph were estimated to have 38 percent more deaths per million vehicle miles than expected, while states that increased speed limits to 70 mph were estimated to have a 35 percent increase.
The estimations are based on comparisons to states that did not hike speeds, although geographic differences may have affected the estimations.
“Whenever vehicle speeds increase, death rates also increase,” said Allan Williams, institute chief scientist. “And the reverse is true. In 1974 when the national maximum speed limit lowered the limits across the country to 55 mph, fatality rates dropped significantly.”
This year’s speeds are the highest the institute has logged since it began measuring them in 1987, said Richard Retting, institute senior transportation engineer. The report highlighted New Mexico, where rural interstate speed limits were changed from 65 mph to 75 mph in 1996.
In 1988, New Mexico motorists’ mean speed on rural interstates was 66 mph, and 6 percent exceeded 75 mph. Their speed increased in 1996 when the speed limit became 75 mph, and by last March, 55 percent of motorists exceeded 75 mph on rural interstates. Sixteen percent of four-wheelers were going 80 mph or more.
“When the institute started measuring vehicle speeds in New Mexico, we didn’t even report the percentage of cars going over 80 because they were so rare,” Retting said.
Institute researchers also studied urban interstates, such as in Atlanta, where the mean speed was 75 mph when the speed limit was 55 mph. Seventy-eight percent of drivers drove at least 70 mph and 18 percent exceeded 80 mph.
“Drivers tend to choose speeds they perceive as unlikely to result in a ticket,” Retting says. “Presumably, differences in the perception of the amount of enforcement among these areas were major factors in the higher or lower travel speeds.”
Researchers point out automakers emphasize the increased performance capabilities of new cars in ads. Average horsepower increased 65 percent between 1980 and 2000, while cars manufactured in 2000 had the highest percentage of vehicles with turbocharged engines.