Last week’s column described what highway departments must consider where snowstorms are an annual event. In this article, we deal with the pluses and minuses of using sand versus salt to treat roads covered with snow and ice.

A large number of chemicals and other treatments are used for ice control. The state Department of Transportation generally uses six — salt (sodium chloride or rock salt), treated salt, calcium chloride, magnesium chloride, magnesium chloride with organic based performance enhancer and abrasives (Sand). Salt is the most common and least expensive ice control chemical. Salt’s ability to melt ice or form brine is highly temperature-dependent.

Salt can be pre-treated or pre-wetted with a variety of liquids to improve its performance. Calcium chloride and magnesium chloride are normally used for this purpose. Pre-treated salt will start to work quicker than untreated salt, will continue to perform at lower pavement temperatures and can generally be applied at a lower application rate.

NYSDOT trucks are now equipped with road temperature sensors to help operators make timely, sensible application rate decisions. This is important because the temperature of the pavement is more important than air temperature.

Abrasives can be natural sand, manufactured sand or iron-ore tailings. Abrasives provide immediate temporary improvement in the frictional characteristics of the pavement surface, but have little ability to melt the snow or ice pack. Also, more frequent reapplication is necessary. Sand piles are usually mixed with 5 to 10% salt to prevent the sand pile from freezing.

While abrasives have a low initial cost, the cost per application is about the same as salt once the increased application rate, salt mixed in the stockpile and mixing costs are considered. The addition of greater fuel costs, more wear and tear on the vehicles and after-season clean-up costs can dramatically increase the total cost to where sand is actually more costly than salt to keep our roads safer. Areas adjacent to certain bodies of water and certain aquatic creatures can also be adversely affected by the use of abrasives.

Furthermore, sand brings with it air pollution, edge of pavement degradation and drainage clogging impacts.

Application rates vary according to several factors, but standard accepted rates are in the 125 to 200 pounds per lane mile for salt and salt with calcium or magnesium chloride and in the range of 750 to 1,000 pounds or more per lane mile for abrasives such as sand. At these accepted application rates, one truck load of salt will be able to cover more than five times the miles that a truck load of sand will cover. That means spreading sand will take more than five times as much fuel and wear and tear on the vehicles as the spreading of salt would. And, when you consider that the sand is mixed with salt, spreading sand will also disperse more than half as much salt as spreading pure salt would. You’re going to get salt no matter what.

There are other considerations as well. Consider the cost of stockpiling the sand in the fall and the considerable costs of clean-up in the spring. Also, the abrasiveness of sand wears off the pavement markings and generally collects in the center of the roadway, obstructing the centerline. Of interest, the villages of Dexter and Brownville near Watertown and the City of Watertown have been using only salt for more than 15 years. The reasoning behind this decision is to save money, primarily in the costs of spring clean-up.

No matter how we clear our roads from snow and ice, there will be some effect on the environment — that’s part of the price we pay for safer winter driving.