Managing Icy Roads

With Salt and Sand 

To better understand ice control and the methods the City uses to provide traction on streets in the community, we must first have some background knowledge of the materials used in the process. 

Sand on its own does not have ice-melting capability. Sand is primarily used as an abrasive to provide temporary traction. Sand works best on hard-packed snow where it can embed itself into the snow and remain there. When used on ice, sand tends to “bounce” when it comes out of the truck and ends up at the roadside. The City uses a salt/sand mixture of approximately 15 percent salt and 85 percent sand. The salt prevents the sand from freezing in the pile and provides some ice-melting capability. This sand/salt mixture is only used in extreme cold weather or freezing rain. 

Pure salt is used on Ramsey’s primary roads and intersections to help control ice. Salt has a practical working temperature of 15 to 20 degrees Fahrenheit. Water usually freezes at 32 degrees, but with the introduction of salt, the freezing temperature is lowered to the 15 to 20-degree range. The surface temperature of the road determines the amount of de-icing chemical needed and how effectively the chemical will work. As temperatures go down, the amount of deicer required to melt a given quantity of ice increases significantly. Salt is five times more effective at 30 degrees than at 20 degrees. 

Before a dry de-icing chemical can act, it must dissolve into a brine solution. Brine is the term used to describe the salt and water mixture. The necessary moisture to accomplish this can come from snow on the road surface or water vapor in the air (humidity). Heat is required to create this moisture. Sources of this heat include the air, the sun, the pavement, or traffic friction. At extremely low temperatures, many of these sources are not available. 

Ramsey, like many communities, is now “pre-wetting” their salt. This is accomplished by placing a brine tank on the rear of the sanding truck to wet the salt when it comes off the spinner. Wetting provides moisture to make brine and speeds up the melting process. In addition, the wet salt has less of a tendency to bounce or be blown off the road by traffic. With pre-wetting, overall savings in lost or wasted salt can be as high as 20 to 30 percent. 

With over 186 miles of roadway and some 860 plus intersections, the City relies on the Police Department and phone calls from citizens to alert the Public Works Department to problem areas that may occur because of frigid temperatures. Traffic can also cause slippery areas by tracking the salt out of an intersection or packing down the snow before the salt can work. Maintenance crews do initial salting as they plow the City roads after a storm, and sometimes, problem areas occur before they can complete the salting operation.