Study: Traffic crashes increased after 2017 speed limit hike on St. Clair County highway
Speed limit increases across rural stretches of highway in 2017 meant an increase in crashes, and St. Clair County was no exception.
In 2017, a Michigan law change boosted speed limits to 75 mph along 600 miles or rural highways, including a stretch of I-69 that connects Port Huron and Flint.
A study published in Traffic Safety Research by Michigan State University researchers examined data before the speed limit change from 2014 to 2016, and the two years after in 2018 and 2019. The year 2017 was skipped due to the staggered implementation of the speed limit increases across Michigan's highways.
Peter Savolainen, one of the co-authors of the study and a foundation professor in Michigan State's Department of Civil and Environmental Engineering, said when other variables such as traffic volume were accounted for, all traffic crashes across the state increased by 5% after the speed limit hikes.
Savolainen said that trend was about the same on a roughly 51-mile of I-69 in St. Clair County, where average yearly crashes increased from 90.67 crashes before the speed limit change to 94 after. The number of injury crashes also increased, from an average of 13.67 to 14.5.
"It's essentially a trade-off, we get to travel from point A to point B more quickly than we would otherwise, but with that there's an increased risk of crashes and result in injuries and fatalities," Savolainen said.
Savolainen said he would be concerned to see further speed limit increases, as an increase in speed limits correlates with an increase in crashes.
St. Clair County Sheriff Mat King, who was not sheriff but was in law enforcement during the traffic limit increases, said he did not notice an increase in crashes around the speed limit changes. Still, he said high speeds usually correlate with higher severity of crashes.
“The higher the speed the more violent the crash," King said.
Distracted and drugged driving also concerns in traffic safety
Since the study concluded, Savolainen said that while traffic volumes decreased nationwide and statewide in 2020 and 2021 during the COVID-19 pandemic, traffic fatalities actually increased, possibly fueled by high-risk behaviors such as drunk, drugged or distracted driving.
King said drugged and distracted driving seems to be on the rise in recent years. He said his department had noticed an increased in drugged driving when marijuana was legalized, as more people were using the substance and driving.
King said motorists using their cell phone while driving continues to be a concern and is the cause of many crashes.
"My deputies report that people who are driving and swerving, it seems like there is just a good of chance of them using their mobile device as were in the past, when you saw someone swerving they might be under the influence of alcohol," King said.
And combining high-risk behaviors with speed creates dangerous driving, King and Savolainen said.
"If you're going faster and you look down at your mobile device for two seconds, compared to if you're going very slow and look down at your mobile device, you're covering much more ground. And obviously the more ground you cover, the more likelihood you are to come across a hazard of some sort, another vehicle or a pedestrian or a stop sign," King said.
Contact Laura Fitzgerald at (810) 941-7072 or lfitzgeral@gannett.com.
This article originally appeared on Port Huron Times Herald: Study: Traffic crashes increased after 2017 speed limit hike on St. Clair County highway
