ROCHESTER, Minn. (KTTC) – This Saturday, get ready for the first snowfall in over 50 days, with predictions of over an inch of accumulation.
Mike Dougherty from the Minnesota Department of Transportation (MnDOT) mentioned that crews have wrapped up their preparations for the winter weather.
“We know it’s coming; it’s just a question of when and how much,” Dougherty said. “Our equipment is ready, and we’ve refreshed our supply of salt.”
Rock salt is one of the main tools used to keep our roads clear in winter. Typically, during a harsh winter, MnDOT uses about 39,000 tons of rock salt across 11 counties. However, in the past couple of years, usage has dropped because last winter was mild. This trend might persist, although crews are using more brine when conditions are gentler.
“Brine usage has been cut down to about half,” he added. “We tend to rely on it more for ice and rain.”
When rock salt is applied to roads or sidewalks, fascinating chemistry happens. Dr. Xavier Prat-Resina, a chemistry associate professor at the University of Minnesota Rochester, explains that the science revolves around ions. These are tiny electrically charged particles that help salt melt ice.
Prat-Resina illustrated the interaction of these ions using magnetic models. The sodium ions, which carry a positive charge, bond solidly with the negatively charged oxygen, while the chloride ions bond with positive hydrogen ions in water.
This connection lowers water’s freezing point, effectively melting the ice. Prat-Resina emphasizes the importance of even salt distribution.
“The more salt you add, the lower the temperature needed to freeze,” he said. “If you just pile salt in one spot, only the ions closest to the ice will work.”
On snowy days like Saturday, Minnesota DOT crews will be on the roads for 12-hour shifts to keep them clear. It’s a busy time as they work to maintain safety on our winter roads.
