AIDC project number:
Nathan Belz
The management of anti-icing and deicing efforts are critical for mobility and safety (Kuemmel & Hanbali, 1992) of travel during the winter season in cold climates. The use and application of salt, sand and related mixtures and derivatives have proven to be highly effective for controlling or removing the development of ice on the roadway surface. The Alaska Department of Transportation and Public Facilities (DOT&PF) must cover an incredibly large state with incredibly dynamic and varied weather and temperature conditions. Historical average low temperatures are below zero for the entirety of November through March. Temperatures routinely reach -40 degrees-Fahrenheit and colder. Though these conditions are not suitable for the use of anti-icing chemicals, shifts in weather patterns have increased the number of days and events during which anti-icing treatments are effective. In contrast, average low temperature for Anchorage is 14 degrees-Fahrenheit in January. Alaska DOT&PF uses roughly 16,000 tons of salt to prep its winter road-sand supply for the entire central region (which includes Mat-Su Borough, the Kenai Peninsula, Kodiak, the Aleutians and southwest Alaska) and cost the state $2.4 million dollars in 2016. Notwithstanding, the Alaska DOT&PF must develop robust and comprehensive plans for winter maintenance operations to maintain and acceptable level of mobility and safety for the traveling public while also operating within a very constrained budget. Several techniques and approaches are used for this purpose including application of deicing and anti-icing chemicals accompanied with snow plowing. Alaska DOT&PF also uses what they refer to as “enhanced brine” which includes carbohydrate derived from beet extract. If applied in excess, anti-icing material may create significantly slippery and wet pavement surfaces. Conversely, if an insufficient amount of anti-icing material is applied it can fail to provide sufficient friction and 10 be ineffective in preventing the bond between ice and pavement surface. Timely information on road weather conditions is necessary for effective anti-icing applications. The current lack of friction data and performance of various anti-icing materials hinders the maintenance personnel from making optimal decisions. Furthermore, there is little if any research to suggest the longevity and dispersal of anti-icing and deicing compounds after they have been applied to the roadway surface (i.e., how long does it stay in place and where does it go postapplication?). It stands to reason that anti-icing and deicing compounds (e.g., salt and sand) are only effective at or above a certain concentration. That is to say, if the amount of salt in solution becomes too dilute, than it no longer retains the capacity to control the development of or melt ice on the roadway. The questions that remain are: 1) how long after applying an anti-icing or deicing chemical does the application remain at an effective concentration; and 2) when is reapplication of anti-icing chemical warranted?
