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Study: 75 mph speed limits leading to more crashes

CEDAR SPRINGS, Mich. (WOOD) — A new study looking at speed limits in Michigan says the increase to 75 mph on some highways has led to an increase in crashes.

Peter Savolainen, a professor at Michigan State University who specializes in traffic safety research, was part of a team that looked at sections of Michigan highways where the limit was increased in 2017.

“The speed limit increases did lead to some of these increases as we saw in crashes and injuries and fatalities,” Savolainen said.

The coronavirus pandemic complicated the research because driving habits changed with more people working from home and reducing travel.

“We looked at three years of data before those increases went into effect, so 2014, 2015, 2016, and then we compared that with two years of post-increase data from 2018 and 2019,” Savolainen said. “We’d initially planned to look at 2020 as well but the pandemic kind of changed things quite a bit.”

Researchers say traffic volumes increased overall in that time period, which likely had an impact on crash numbers, along with other factors like distracted driving.

“When we look at the aggregate data where the speed limit increases went into effect, we saw an increase in total crashes of nearly 17%. With that being said, we also saw traffic volume went up considerably there by nearly the same amount,” Savolainen said. “The most troubling part is that we saw a disproportionate increase in the number of fatal and severe injuries, so that was more on the neighborhood of 25%.”

Researchers also found a greater increase in the range of speeds on the 75 mph sections of roadways.

“You’ve got some subsets of drivers who will go five, 10 miles per hour over and so if you increase the limit, it’s not as if the speeds are suddenly going to be more in line,” Savolainen said.