Photo:  Cook County

By Highway Engineer Krysten Foster from Cook County MN - November 30, 2019

With the change in seasons comes questions about Cook County’s current use of salt-sand mix to treat icy roads. Thankfully, Minnesota has a strong and nationally-respected road research community working to address this issue.

Each year Minnesota cities and counties dedicate a small percentage of statewide funds ($4 million in 2019) to an annual program administered by a committee known as the Local Road Research Board, or LRRB. Currently, the LRRB and the Minnesota Department of Transportation (MnDOT) are cooperatively researching road salt alternatives and chloride reduction options, including potassium acetate, and equipment alternatives such as reversible plows and a v-shaped slurry spreader.

Unfortunately, prior studies have not yielded any viable alternatives. In 2017, a LRRB-supported

research project led by Montana State University’s Western Transportation Institute concluded that environmental impact, product cost, application method, or a combination of these three barriers prohibits widespread use of several road salt alternatives used on airport runways and bridges, including potassium acetate, sodium acetate, potassium formate, sodium formate, urea, glycol-based deicers and succinate-based deicers. With that information in hand, Minnesota’s road maintenance professionals continue to search for an effective and affordable road salt alternative.

Will any of this work lead to changing Cook County’s winter maintenance practices? Perhaps someday. The crux is that, in addition to looking at product cost and potential environmental impacts, the highway department must consider effectiveness on low-traffic roads and increased equipment costs before proposing use of any road salt alternative. For example, the anti-icing brine applied to some high-traffic freeways may not work as effectively on a shady, low-traffic highway that is not plowed as frequently.

Additionally, ordering different shapes of boxes or other equipment add-ons for county plow trucks could limit our ability to efficiently haul gravel during the summer maintenance season.

As we continue to investigate viable options, Cook County meets public safety needs and minimizes road salt use by applying a mix of seven to 10 percent sodium chloride and 90 to 93 percent fine-grained sand. This mixing ratio, combined with comparatively lower traffic levels, leads to a reduced risk of toxic chloride concentrations in local lakes, rivers, and streams, as compared to metropolitan areas where road maintenance agencies regularly apply 50 percent or greater chloride mixes.

In an average winter, Cook County uses 200 to 250 tons of road salt on its paved highways. (Road salt is rarely applied on gravel roads.) On the other end of the spectrum, Hennepin, Ramsey, Washington, Scott, and Dakota Counties each apply thousands of tons of road salt each winter.

We understand that winter road maintenance is a complex issue. Cook County is committed to public safety and environmental stewardship, and we continually strive to improve our service in both these areas.

If you have questions about this, other county road issues or research funding ideas, please call us at 218-387-3014. If you travel on a road that appears to need attention outside of normal business hours, we ask you to call the Cook County Sheriff’s Office at 218-387-3030.
The sheriff’s office will follow up with highway department staff. We are fortunate to have a hard-working team of 15 maintenance workers and mechanics who dedicate many hours away from their families to provide winter maintenance services for residents and visitors.

Lastly, the highway department thanks everyone who drives vigilantly, especially during the winter season. Snow removal equipment operates with significantly larger blind spots than an automobile, and plow or grader drivers sometimes operate in reverse to adequately push snowbanks or spread salt-sand mix at an intersection. Please give them room – at least five car lengths – and use extra caution when approaching or meeting any snow removal equipment. By working together, we can navigate the slippery slope of winter road maintenance and better prepare for the winters to come.

For more information on this and other county highway issues, visit the highway department’s page at https://co.cook.mn.us. Information on statewide road conditions is available on MnDOT’s 511 statewide travel and road condition site, https://www.511mn.org/.