As discussed in greater detail in the final report, extremely cold winter storms (below about 10°F) bring about different considerations for taking care of roads than warmer winter storms, where granular salt and salt brine are cost‐effective measures of melting snow and ice when used in combination with other operations (e.g., plowing). At temperatures lower than about 10°F, either extremely large quantities of salt are needed or no amount of salt can melt snow or ice pack. Best practices for using chemicals during extremely cold winter storms include: waiting until the end of the storm, using deicers in daylight hours only, mixing salt with MgCl2, CaCl2, and/or agriculture by‐products, and using high application rates. Despite their environmental and hidden costs (air pollution, sedimentation, spring cleanup & disposal), abrasives are frequently used during extreme temperatures to provide temporary traction. Best practices for using abrasives during severe cold includes prewetting with liquid deicers (although not plain salt
brine—it may freeze) or hot water. Innovative strategies continue to be tested at severe temperatures, including conductive pavements and geothermal systems, which have demonstrated to be potentially effective tools.
Using salt to keep roads clear works very well, down to approximately -12.2ºC (10ºF). It will also work at lower temperatures but it requires higher volumes and becomes less cost effective. When the temperature gets extremely low state agencies tend to: plow the roads, rely on abrasives, and/or use high volumes of salt. In urban areas with high traffic volumes abrasives are ineffective and other strategies result in the over usage of salt, equipment and manpower. Additional strategies need to be identified for maintaining roads in extreme temperatures. Recommendations need to take into account that some strategies may be more efficient and effective for low-volume versus high-volume roads.
This research is expected to advance the knowledge base for winter maintenance best practices under extremely cold temperatures, and thus help maintenance agencies address the challenge in meeting multiple priorities in safety, mobility, environmental stewardship, and infrastructure preservation in a fiscally responsible manner. By identifying and promoting best practices, it is expected to help improve the LOS on highways, reduce the winter maintenance costs, and reduce the corrosion and environmental impacts due to snow and ice control operations.
The goal of this project was to review best management practices for maintaining clear roads at extremely low temperatures and develop cost effective strategies for getting the roadway to a bare/dry condition in extreme temperatures and keeping it at that condition.
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