The 65-mph speed limit on Idaho's rural interstates did not lead to more traffic deaths during the first year of the higher speed limit, a state Transportation Department study shows.
But interstate accidents increased slightly during that same period, the Idaho State Police said, although they did not provide specific figures.Fatalities totaled 31 on rural freeways from May 1987 to May 1988 - the 12 months after the speed limit on Idaho's 550 miles of rural interstate was raised from 55 to 65 mph. That is the same as the previous year, said Dave Amick, Transportation Department safety specialist.
Interstates in urban areas, such as Boise, retained the 55-mph speed limit, but deaths went from two to four during the same period of time. On the other highways, where the speed limit is 55 mph, deaths dropped from 88 to 83.
"Statistically, there is not enough of a difference to shake a stick at," he said. "There is no discernible difference."
Amick said Idaho departed from a national trend, which shows the number of fatalities increases with the speed limit.
He attributed Idaho's good record partly to safe design of the freeways. Idaho interstates were designed for traffic moving 70 mph.
However, Lt. David Rich of the Idaho State Police said injury accidents had become more severe because of the higher speeds.
"The stopping distances are longer at higher speeds," he said.
A danger of the 65-mph speed limit is that some drivers get used to traveling at that pace and do not slow down when weather conditions change, Rich said.