In this article, Civil Engineer, Thomas Lyden provides an overview of winter maintenance operations. His discussion includes two strategies for snow and ice control, anti-icing and de-icing, and how failure to adequately address hazardous road conditions sometimes manifests itself in our forensic casework.
Winter Roadway Maintenance - Expert Article
Snow, ice, and slushy pavements are among the predominant hazards associated with winter weather driving. The USDOT Federal Highway Administration data reports an average of 1,705 deaths and 138,735 injuries per year due to snowy and icy roads.1
When properly executed, winter maintenance operations can dramatically improve roadway safety. Agencies that reasonably expect to experience snow and ice conditions must have the requisite resources, policies, and procedures in place to provide for the safety of the motoring public. As it relates to forensic casework, anti-icing and de-icing activities are issues commonly in dispute, and will serve as our focus in this article.
Snow and Ice Control Strategies
To combat the hazards of winter weather, state, county, and local agencies employ a variety of strategies to return pavement surfaces to pre-event conditions as quickly as possible.
Anti-icing is a proactive strategy to controlling snow and ice. By applying chemical treatments to the pavement before, or soon after a storm begins, the formation of a bond between the snow and ice with the pavement is prevented or delayed. Chemical treatments can generally be applied from a few hours to up to three days before a winter storm. This strategy results in safer roads and a more effective and efficient winter maintenance program.
The most common chemical treatment for anti-icing is the application of brine to the pavement. Brine is a mixture of sodium chloride (rock salt) and water. Anti-icing is particularly effective at locations susceptible to frost or black ice, such as bridge decks, high elevation locations, and shaded areas.
De-icing is a reactive strategy performed after a storm begins and a bond between the snow and ice with the pavement has already formed. The resulting “snowpack” on the roadway is far less safe than lightly snow covered or slushy roads and requires more resources to break, rather than prevent. De-icing may require two to five times the amount of chemical material as anti-icing.
De-icing typically consists of plowing snow and slush off the roadway along with the application of chemicals and/or abrasives. Snow and ice control chemicals work to melt ice and lower the freezing point of water. Sodium chloride, or rock salt, is the most common de-icing chemical and is most effective at temperatures above 15 °F. Other chemicals including calcium chloride and magnesium chloride are more effective at lower temperatures.
Winter Maintenance Operations Forensic Investigations
The adequacy of anti-icing and de-icing activities is frequently disputed in our forensic casework. Our highway and municipal engineers are called upon to determine if agencies took the appropriate preventative and corrective actions based on the conditions leading up to an incident. Working with our experts specializing in vehicle dynamics and crash reconstruction, Robson Forensic may also be able to determine if driver actions, in consideration of roadway conditions, were a significant cause of the incident.
To discuss your case with a technical expert, please contact the author of this article or submit an inquiry.
Civil Engineer & Highway Engineering Expert
Thomas Lyden is a civil engineer with an impressive background covering the entire lifecycle of highway infrastructure. Through his 35 years of professional experience, Thomas has conducted traffic studies to evaluate the need for and safety of new and existing roadway systems, conceptually designed roadways and intersections, administered new construction and maintenance projects, and also oversaw maintenance operations for winter weather, vegetation growth, and infrastructure conditions. He has performed these duties as a consulting engineer as well as a Department of Transportation engineer. Thomas applies his expertise to expert witness investigations involving the design, construction, and maintenance of roadways and transportation infrastructure.