Anti-icing involves pre-treating a road

before

the freezing weather or storm arrives with the goal of limiting or preventing the buildup of ice. Successful anti-icing efforts require accurate timing and good judgment about when and where to treat, relying on weather forecasts, field sensors, and in-field measurements or observations to predict when a storm will hit and its severity.

Studies by various agencies and institutions have identified several benefits of a sound anti-icing strategy:

Anti-icing can be more effective when coupled with a Roadway Weather Information System (RWIS). An RWIS helps to make informed decisions about when and where to deploy materials, crews and equipment.

While an anti-icing strategy coupled with an RWIS can be beneficial, there are some drawbacks associated with RWIS:

Anti-icing systems can be either mobile truck-mounted spray rigs, capable of covering large areas where needed, or fixed spray systems that will treat specific problem locations. Both use a chemical that can lower the freeze point of water, requiring a storage tank for the chemical. Generally, a 6,000-gallon capacity tank with agitation and circulation capabilities is used. However other sizes are acceptable, depending on specific local needs and conditions.

The equipment for a mobile system consists of a truck-mounted tank with a spray boom and controls for accurate calibration. Cost-effective dual herbicide/anti-icing spray units have been designed and built. In such dual-use systems, it should be noted that the chemicals used for anti-icing can be corrosive and thorough cleaning between seasons is necessary.

Commercial vendors can supply a large variety of types and size rigs suitable to the section’s needs.

FOD

purchases major equipment for all snow and ice control methods.

There have been marked advancements in the use of fixed anti-icing systems in the past few years. Fixed systems have been placed at toll plazas, super-elevated bridges and steep hills where maintaining vehicle traction is critical.

These systems use the same chemicals available for mobile anti-icing systems. They are designed and installed at problem locations and can be linked with RWIS to assist in predicting conditions favorable for treatment. Depending on the complexity of the RWIS equipment, the system can be activated remotely or automatically.

The spray systems themselves vary in complexity, but will spray the anti-icing chemical from fixed points onto the road’s surface. Traffic, in turn, will spread and track the chemical over the designed area providing the desired effect.

Fixed systems can be installed during new road construction or added at existing problem locations. Vendors specializing in fixed anti-icing systems can be found on the Internet.

De-icing methods generally involve the use of chemicals to speed the melting process after snow pack or ice has formed on a road. Liquid chemicals with similar spray equipment can be used for de-icing, provided they can be applied at sufficient pressure to cut though the ice or snow pack. Caution must be exercised during de-icing since spraying liquids on top of the pack may cause the road to become slick. The use of dry solid chemicals and pre-wetted abrasives in conjunction with de-icing will speed the melting of the snow and ice pack. This practice will improve the de-icing process and reduce the time it would take to melt naturally