There are two ways we treat the roads during winter called anti-icing and de-icing.
Before a storm, we anti-ice the roads by applying a liquid solution to them. This solution prevents snow and ice from binding to the pavement and lowers the temperature that water freezes. The reason we apply a liquid and not solid salt is that the dry salt is blown away or bounces off the roads when applied before precipitation moistens them. Once precipitation begins, we begin to apply rock salt which requires moisture to be effective.
During and after a storm, we work to de-ice the roads. We remove the ice and snow from the surface of the road by plowing and applying additional materials to the surface of the roads. This helps to loosen the ice and snow from the pavement, while also lowering the freezing point of water.
You may also see some materials spread along a cleared highway after a snowstorm. This post-storm treatment is applied to the roads to prevent them from re-freezing during nighttime.
There are 5 types of materials we use to treat the roads for snow and ice.
- Rock salt breaks up ice and prevents it from sticking to the pavement.
- It is widely available, effective, and inexpensive compared to other di-icing/anti-icing materials.
- However, it is corrosive and can harm the environment if over-applied. It also does not work well at lower temperatures.
Liquid Magnesium Chloride
- Liquid magnesium chloride prevents snow and ice from sticking to the roads.
- It works in lower temperatures, and is less harmful to both the environment and snow plows.
- However, it is expensive and must be applied at specific times.
- Brine prevents snow and ice from sticking to the pavement.
- It is effective for pre-treatment, and easy to apply to the roads.
- It is less expensive and has fewer restrictions on when it can be applied.
- However, it does not work well at extremely low temperatures.
- Sand is inexpensive and effective at increasing traction at lower temperatures.
- However, it does not melt snow and ice, and loses its angularity, and thus its traction, rapidly.
- As sand can clog drains, it must be removed from the roadway, roadsides, and storm drains and disposed of.
Pre-Mix (Rock salt and calcium chloride)
- Pre-mix is used in “reduced salt” areas, and in areas of lower air temperatures.
- It is less harmful to the environment than other materials, and effective at lower temperatures.
- However, it is an expensive material that has to be stored and kept dry.