It’s become common to hear that “one-in-100-year events” are occurring in five-, 10-, and 15-year periods. Scientists identify these extreme weather events based on the historical record of weather in a particular region. A “return time” is a commonly used metric of probability; for example, a 100-year return time means that in any given year, there is a 1-in-100 chance of the threshold being reached. Potential connections between a warming Arctic and mid-latitude weather are the subject of active research as well as a workshop held and summarized by the National Academies of Sciences, Engineering, and Medicine.
Getting ready for winter
In some places, snow and ice are inevitable. Other locations may only see winter weather once every few years or less. 2021 brought unexpected snow to places like Galveston, Texas. No matter where winter weather happens, it brings concerns about safety as well as potential economic disruption.
Airports can find direction on everything from planning to storm recovery in the TRB Airport Cooperative Research Program’s (ACRP) A Guidebook for Airport Winter Operations. The report details Federal Aviation Administration (FAA) requirements and guidance as well as the levels of investment needed to implement an effective winter operations program. It also provides tips for managing the overall passenger experience.
In 2017, TRB’s Transit Cooperative Research Program (TCRP) synthesized methods and procedures to maintain transit stops and infrastructure during extreme weather. Case studies showed that 26 of the transit agencies surveyed for Managing Extreme Weather at Bus Stops had plans for response to snow, ice, rain, wind, heat, and hurricanes. One even included plans for tsunamis. The report offers a state-of-the-practice report on resilient transit systems’ management of extreme weather events, associated planning, management responsibilities, efforts to respond, standards and specifications, associated legal claims, and communication with customers.
An ounce of prevention will pay off
Winterization can begin as early as road design. Laura Fay of the Western Transportation Institute and a committee member of TRB’s Standing Technical Committee on Winter Maintenance says, “Having someone who has sat behind a plow at the table when you’re making pavement decisions makes a huge difference. There is a lot of learned knowledge that cannot be replicated and will save effort later on.”
Using a liquid brine on roads up to 24 hours before a storm event is a well-known best practice to greatly reduce the effort required to clear the roads by preventing snow or ice to form a bond with the road.
“It’s really easy to show the cost effectiveness of using liquids. It usually starts with a single motivated person, and then word spreads quickly,” says Fay. “Sitting next to someone at a training course or talking with a vendor is how so many of these ideas are spread. There’s an argument to be made for justifying the cost of travel for training or conferences just to share ideas and talk through them.”
Permeable interlocking concrete pavement (PICP) allows water to drain from the surface into an aggregate base and subbase layer. A study published in Transportation Research Record (TRR) shows that PICP surfaces can prevent black ice from forming as well as requiring less deicer than asphalt. The article finds PICP design offers a lower risk for pedestrians and vehicles alike.
Appearances can be deceiving. Another study published in TRR showed that compacted snow bonds more strongly to Permeable Friction Surfaces, yet the friction was notably greater than traditional dense graded pavement even without the use of salt. They will look more white and snowy, which may contribute to unnecessarily high application rates of salt.
Fay is one of the friction studies’ coauthors. She notes the importance of matching the pavement capabilities to the treatment. A liquid, for instance, may need to be applied differently on an open graded surfaces, such as fan spray application to keep the product on pavement surface, or use a courser salt to prevent it from working its way into cracks. No single solution fits every storm or pavement.
Plowing through the research on preventing and removing snow and ice
Preventing and removing the snow and ice from winter storms is a growing concern for agencies that are responsible for the safety and resilience of roads all across the United States. TRB’s National Cooperative Highway Research Program (NCHRP) offers a number of resources.
Performance Measures in Snow and Ice Control Operations presents approaches for monitoring the performance of and customizable measurements for meeting snow and ice control activities and objectives. Collecting and quantifying relevant information allows highway agencies and contractors to monitor the level of performance and make appropriate adjustments to effectively manage resources for snow and ice control operations.
Monitoring and measuring the performance also assists agencies in establishing level-of-service targets and better communicate them to stakeholders in the community. TRB offered a webinar on the report that featured practices and potential approaches from state departments of transportation on their use of snow and ice performance measurements.
Even neighboring jurisdictions can have significantly different approaches to providing winter services, notes NCHRP’s Alternative Delivery Methods for Winter Maintenance Operations. The digest presents a decision-making framework to guide public road agencies in their delivery of these services.
Forthcoming research from an active NCHRP project will provide a primary source for guidance on all aspects of snow and ice control applications to incorporate substantial advancements in plowing equipment, materials handling and storage, communications, technology, and strategies since the AASHTO Guide for Snow and Ice Control was published in 1999.
Keeping an eye on environmental sustainability
Salting the roads is a common approach, but there are environmental concerns with the process. An earlier NCHRP report, Strategies to Mitigate the Impacts of Chloride Roadway Deicers on the Natural Environment, documents the range of methods, tools, and techniques used by transportation agencies to minimize the environmental impact of chloride-based roadway deicers.
Fay is enthusiastic about the opportunities for non-chloride solutions. “Some folks are researching heated pavement, either geothermally, solar power, or other sustainable energy sources. For example, an airport has a test section of heated pavement with carbon fibers in the mix. There are sustainable solutions that could be better funded.
“I tell students, you really have the opportunity to change the way we do things. We’re at the precipice to do something new and exciting. We just haven’t figured it out yet.”
Airports need solutions for managing stormwater runoff containing deicers
To ensure safe and efficient operations, deicing and anti-icing agents are applied to aircraft and airfield pavements. Yet airports must also be able to manage stormwater runoff containing these agents. ACRP’s Winter Design Storm Factor Determination for Airports helps airport operators develop stormwater management systems that balance development and operational costs with performance and environmental considerations.
In addition, presentations from a recent TRB webinar on the topic are available. Attendees heard about pavement and aircraft deicing source reduction, deicing stormwater runoff containment and collection, deicing runoff treatment and recycling, and deicing runoff system components.
Even more information on managing and treating airport stormwater impacted by deicing can be found in ACRP’s Guidance for Treatment of Deicing-Impacted Airport Stormwater. The report identifies available and emerging onsite and offsite technologies for treating stormwater impacted by airport deicing activities, evaluates the performance of available technologies, and provides guidance to help airports select technologies for treating deicing-impacted stormwater. An anticipated ACRP project will update this information.
Get ready for next winter with TRB
Join experts like Fay and become a friend of TRB’s Standing Technical Committee on Winter Maintenance. Friends of committees receive updates on and can volunteer to participate in committee activities.
“Something we’ve been talking about in the committee is the idea of equity. If we’re really equitable, we need to be taking bike paths and pedestrian routes into consideration,” she notes.
Get involved in this work with the Cooperative Research Programs. Look for ongoing information on new projects, requests for proposals, or to nominate yourself or others to serve on a project panel. Submit problem statement research ideas and find new announcements in TRB’s weekly newsletter or on the homepages for the ACRP, NCHRP, and the TCRP.
TRB is planning an international conference and peer exchange on road weather and winter maintenance. Look for it in the coming months under TRB’s events.
TRB reports cited in this article:
Articles published in TRR:
TRB standing technical committees:
Active and anticipated CRP projects:
National Academies of Sciences, Engineering, and Medicine resources:
This Summary Last Modified On: 3/4/2021