Winter is closing in, and with it comes the annual spike in skid-related crashes on Michigan’s curved roadways. A new study out of northern Michigan suggests there’s a simple, tech-driven way to get drivers to slow down before trouble hits: flashing LED warnings installed right on curve signs.
Researchers found that when these lights activate during slippery conditions, drivers ease off the accelerator, exactly the kind of behavioral shift road engineers have been chasing for years.
Curves Are a Winter Danger Zone
From 2018 to 2022, Michigan recorded 128,517 winter-weather crashes on curved roads. Those incidents led to 175 serious injuries and fatalities, along with more than 1,300 additional injuries. Highway engineers have long known that horizontal curves, even on flat terrain, are risk magnets, especially when the posted speed and the advisory curve speed differ by 10 mph or more.
The problem gets worse once snow and ice enter the picture. Reduced pavement friction makes it easier for vehicles to drift out of their lanes, and more than a quarter of fatal crashes nationwide involve horizontal curves.
Testing New Tech on M-32
To see whether real-time visual alerts could make a dent in this crash pattern, Michigan State University researchers tested flashing LED border lights on signs along a 1.7-mile stretch of M-32 west of Gaylord. The highway runs at 55 mph, while the curve itself carries a 45 mph advisory.
Sensors tracked pavement conditions and triggered the LED lights automatically in 30-minute cycles whenever snowfall or icy moisture was detected. Testing happened during early-morning storms and periods with temperatures hovering in the upper 20s to low 30s.
The result: drivers slowed down in measurable, meaningful ways.
Small Slowdowns, Big Impact
When the LEDs flashed, eastbound drivers reduced speed by an average of 1.5 mph, and westbound drivers by about 0.9 mph. The effect was even stronger among the fastest third of drivers, who slowed by an average of 1.7 mph.
For Timothy Gates, MSU professor and coauthor of the study, that subtle shift is exactly what engineers hope for.
If you make drivers slam the brakes, you risk causing the very crash you want to prevent. But getting motorists to ease off early, that’s invaluable during winter conditions.
Useful but Not for Every Curve
MDOT traffic and safety engineer Garrett Dawe says the findings confirm what the department suspected: dynamic warnings help. But there’s a catch, a cost.
The sensor-light systems aren’t cheap, and mass deployment isn’t on the table. MDOT plans to reserve the technology for locations with a clear safety problem or severe crash history.
In the meantime, the department is rolling out lower-cost fixes at curves: durable skid-resistant pavement coatings, more reflective signage, and visibility upgrades.
MSU’s next project will focus on rural highways that cut into small towns, studying new traffic-calming tools for school zones, crossings, and areas with heavy pedestrian or bicycle activity.
