Rock salt versus salt brines: What's best for road safety?

By Erin Cassidy, AccuWeather staff writer

January 12,2017, 12:56:53PM,EST

 

 As the country drudges through the winter, transportation departments located in the season’s icy grip are implementing new strategies to keep roadways safe.

Salt has always been applied to roadways since it lowers the freezing point of any water it comes into contact with. Traditionally, this was accomplished by applying solid rock salt before and after snowfall to reduce ice and snow. However, this strategy is only effective when temperatures are above 15 degrees Fahrenheit.
These actions would be considered de-icing, which is removing snow and ice after the weather event has occurred. The limitations of these actions have led transportation departments to implement new strategies to combat winter weather.
However, a study sponsored by the New York State Department of Transportation determined that, “In recent years, there has been a growing transition from reactive strategies to more proactive strategies.”
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A worker at the Pennsylvania Department of Transportation facility dumps salt into a truck as they make preparations for an expected winter storm, Thursday, Jan. 2, 2014, in Philadelphia. (AP Photo/Matt Rourke)

Roadway crews are now using more effective measures to prevent dangerous road conditions. Using salt brines, which is any liquid salt mixture, before anticipated snowfall was discovered to be more effective than using solid rock salt.
Brines have the same melting characteristics of solid rock salt, but since it is applied in liquid form, the salt can begin to work immediately. The brines are also more effective in lower temperatures.
The use of brines is known as anti-icing or pre-wetting measures.
Anti-icing can be accomplished by using traditional salt brine (usually a 23 percent salt solution, derived from rock salt) and applying to roadways in preparation for snow and ice. Alternate sources of brine, including agricultural by-products such as beet juice, are also being used in certain states.
Using salt brines proves not only to be more effective on roads, but it is also cost effective. It takes four times less salt to prevent ice accumulation than to remove ice after it has formed.
“Anti-icing is currently recognized as a pro-active approach to winter driver safety by most transportation agencies. Pre-wetting [using salt brines] has been shown to increase both the performance of solid chemicals and abrasives, as well as their longevity on the roadway surface, thereby reducing the amount of materials required," the study said.
Combined with accurate weather forecasts, anti-icing is a more proactive technique for winter transportation safety.
“Brine provides improved road surface conditions and allows for safer travel,” the study concluded.