Less than 20 years ago, U.S. crews had one basic response to a winter event that threatened to slicken roads—plows, salt and more salt just in case. Trucks went out in a race against the chance that ice would bond to the road, creating the “black ice” that helps create 400,000 cold weather-related crashes a year.
But technology has come a long way since then. For instance, when Colorado was smacked with three snowstorms this month, road crews used a year-old software test program, the Maintenance Decision Support System (MDSS), to make better decisions in deploying equipment and deicing chemicals.
With the help of data gathered by meteorologists and roadside sensors, cameras, pavement thermometers and global positioning system-equipped trucks and plows, computers suggested when to expect snowfall, where plowing should be done first, and how much or what type of deicing chemical to use.
Granted, with such extreme amounts of snow, deicing could only do so much. But thanks to reliable MDSS forecasts, “we stocked up on deicers and sanding material, fueled our equipment and refueling tanks, sent some employees home and got everyone on snow shift early,” says Phillip Anderle, Colorado Dept. of Transportation deputy maintenance superintendent. “We also chained up some of our equipment early.”
MDSS, deployed since 2002 as part of a pooled research effort of a few states, is being tested in a majority now. It is part of a paradigm shift regarding snow and ice road management that began in the early 1990s, says Paul Pisano, road weather program manager for the Federal Highway Administration. Now, the push for high-tech solutions is evolving fast. Alternatives to salt are multiplying, and advanced tools to anti-ice rather than deice are gaining traction. “We have [gone from] being completely reactive—waiting for snow to fall—to being proactive and tackling the event head-on,” says Pisano.
The seeds for the shift were planted with the Strategic Highway Research Program in 1988, which emphasized the need for new snow and ice strategies for roads. With that in mind, FHWA and the National Cooperative Highway Research Program (NCHRP) sponsored scanning tours to Europe and Japan in the 1990s.
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Automated sprays embedded in bridge
They discovered anti-icing strategies that emphasize pre-emptive applications of chemical deicer, often in liquid form, before a storm strikes. A handful of pioneering states, such as Iowa, Pennsylvania and Minnesota, led the push to implement the strategies here. Slowly but surely, more states are trying different deicing chemicals, fixed automated systems and redesigned vehicles to deploy them and technology to predict when and how much to use them.
Because it is cheap, road salt will always be a staple, say officials. But with concerns about corrosion and pollution, an array of alternatives and additives have proliferated. They include a variety of chlorides, salt brine and vegetable additives. They vary according to efficacy, corrosiveness, environmental effects and price.
A DEICING CHEMICAL SAMPLER MENU
|Salt: The cheapest option. Effective until 20°F or below. $30/Ton*|
|Brine: Mixture of salt and water applied in advance of snow.|
|Pre-wetted Salt: Reduces salt use by eliminating bouncing off the road.|
|Calcium Chloride: Used below 20°F. Often combined with salt. $91/Ton*|
|Magnesium Chloride: Often used with sugar beet/cane molasses additives to reduce. its corrosive effects and help adhesion. $46-$100/Ton|
|Potassium Acetate: Low corrosion, environmentally friendly. $601/Ton*|
|Calcium magnesium Acetate: “safe” as tap water. $1000/Ton*|
So complex and varied is the selection that NCHRP will this spring offer a computer-based training program developed by the American Association of State Highway and Transportation Officials’s Snow and Ice Cooperative Program. Leland Smithson, SICOP coordinator, says the program will help crews make decisions on what material to use in what environment, based on parameters like heavy metal content, temperature limits or pollution potential—plus sizes and types of waterways, flora, fauna and soils affecting the road.
Another program will help crews consider 10 types of snow and ice, road conditions, air moisture patterns and other factors that affect deicing. SICOP previously released a program to supplement the Road Weather Information Systems (RWIS) by helping crews interpret data from pavement sensors and roadside stations—vital components of MDSS.
Black ice weapons arsenal includes customized deicing mixers and dispensers.
Richard J. Nelson, assistant director of operations for Nevada DOT, says weather predictions used to “stop 30 ft above the ground....We are working with the meteorological community to get it down to the ground.” Differences in pavements—and chances of black ice—vary from one road segment to the next according to vegetation, alignment, water sources, time of day and other factors.
New York State has 60 RWIS locations and is in its second year of testing MDSS technology, says Robert Selover, transportation systems management director for NYSDOT. “We are working with two vendors to iron out the bugs,” he says, and crews are being trained to effectively use the data. “If a driver says, ‘the snow is slushy, not bonding,’ then we’re doing a good job,” he says. The vendors, each with $25,000 contracts, will install sensors at five sites.
As technology helps crews determine where and when to de-ice, vendors are responding to the growing market for deicing options. Minneapolis-based Cargill Inc. partnered with Michigan Tech University to develop and commercialize an epoxy-aggregate application invented by a professor. It is applied to a road in advance of a storm. Sponge-like, the aggregate stores and releases the deicing chemical of choice when needed.
Crews apply patented epoxy aggregate deicer to road in anticipation of winter storms.
A report by Asset Insight Technologies, a winter highway maintenance consultant, found that nine test installations in six states resulted in no ice-related accidents and no concerns about chemical-related slickness. Company co-founder Wilfred Nixon says more data must be accumulated. “There are times when it’s impossible to put chemicals down before a storm in time. If it begins with rain, liquids will wash off,” he says.
The Virginia Transportation Research Council tried to test the product on Interstate 81, but “there’s been no snow or ice events to speak of,” notes Michael Sprinkel, VTRSC associate director for materials. It is now testing the product on two controlled sections of Blacksburg’s Smart Road in a $125,000 project.
“It could be the biggest and most substantial advancement since the invention of the snow plow,” says John Bray, special assistant to the district engineer for Minnesota DOT. Inspired by Wisconsin tests, MinnDOT tried the epoxy on an Interstate 535 on-ramp near Duluth two years ago. During a snowstorm, “the ramp was melted and wet,” says Bray. But he notes that greater efficiency in applying the materials is still needed. “The epoxy is poured by hand, then the aggregate is shoveled on by hand, and a machine evens it off,” he says. “It takes a day and a half [and] it has to be applied quite precisely.”
Bob Persichetti, Cargill SafeLane general manager, says the product is still a work in progress and that efficient mixing is a goal. “Our goal is to become a ‘line item’” in DOT budgets and airport budgets for runways, he says.
Another product received some bad reviews when it first debuted more than 20 years ago in the U.S. Verglimit is an additive for new asphalt consisting of pellets of calcium chloride plus other materials. It mixes with moisture to form a dilute salt solution. In 1988, media reports said New Jersey State Police blamed the product...