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SPECIAL REPORT: CLEAR ROADS, CLEAR ISSUES
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Less Brawn, More Brains
According to the Salt Institute, the key to achieving safe roads with minimal side effects can be summed up in two words—sensible salting. That is the name for the program the institute initiated in 1992, and through which it claims to have trained more than 100,000 American and Canadian snowfighters. Sensible salting emphasizes properly covering salt supplies, correctly maintaining all equipment, calibrating spreaders accurately, applying salt appropriately, and being concerned about the environment as well as public safety. All that does make sense, except it is being promoted by an organization representing salt producers, who you think would prefer their trade group push practices that result in more salt used, not less.
“Sensible salting in a sense is out of our favor,” the Salt Institute’s Mort Satin said. “But the industry is in this thing for the long run. They don’t want to be labeled as bad guys. They feel there’s nothing else they can do except minimize the impact, because if they don’t, the negative environmental effects are going to hasten the demise of the use of salt on roads.”
Satin said the institute had just finished a large study with the University of Waterloo in Canada that verified with hard data the benefits of sensible salting. Although Satin sounded trustworthy, a call was placed to the University of Waterloo’s Mike Stone, who headed up the study. Stone confirmed Satin’s analysis.
“We drilled a number of holes and looked at groundwater concentrations and chloride loadings in soils adjacent to various road types,” Stone said, “and what we found was that if you reduce the loading by 25 to 40 percent in salt vulnerable areas, you’ll get a 25 to 40 percent reduction in chloride transfer in the adjacent soils and therefore into the water table. This is one clear example of how the impact of road salt can be mitigated to a certain extent.”
While road salt may be old school, techniques for reducing its use now include technological innovations of impressive range. Many of the new systems are being evaluated through Clear Roads, a research project supported by funds pooled from state highway agencies. Paul Brown of the Massachusetts Highway Division serves as chair of Clear Roads’ technical advisory committee, and even in an e-mail interview, his enthusiasm for the work came through.
Responding to a question about research into snowplows with multiple blades, Brown wrote, “The concept is radical and a significant move into the future. This is a huge undertaking for any agency, and people do not immediately embrace change. It will take some time for agencies to embrace but once people see the cost savings it will be apparent that [the multi-blade concept] should be part of a snowfighter’s tool box.”
Clear Roads is also looking closely at zero-velocity spreaders, which release salt at the same speed but in the opposite direction that a truck is traveling. With the two speeds cancelling each other out, the effect is like a stationary truck placing the salt on the road—no bounce, no scatter.
“The research will go a long way toward establishing the value this type of spreader has in a fleet,” Brown wrote. “I am sorry to say [the Highway Division doesn’t] have any zero velocity spreaders. I wish we did. They may be the most effective tool for applying deicing materials to high speed roads.”
Not all technology employed in the field is new and hot out of the testing facility. Road weather information systems have been around for more than two decades, but they remain a tremendous asset. In an RWIS, a weather station set next to the highway works in conjunction with a pavement sensor to provide real-time, location-specific information about conditions in the air and on the ground, allowing transportation officials to make smart decisions about when and where to apply salt. Many states rely on them extensively, including Maine, which now has nine RWIS sites. According to MaineDOT’s Brian Burne, the state spent $270,000 installing the systems and is spending $14,000 annually to calibrate and maintain them.
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Roadside Assistance Small, unmanned weather stations are increasingly popping up on the sides of highways as transportation agencies invest further in road weather information systems or RWIS. Data from the stations and associated pavement sensors help determine how and when to treat specific sections of road. Photo courtesy of Adirondack Council |
“We have found them to be a good tool,” Burne wrote, “especially for remote or problematic locations.”
States now are also routinely doing pre-wetting and anti-icing, although a recent incident in Vermont points to the potential for newer snow and ice practices to be misinterpreted by a public accustomed to traditional road salt use. On January 4, 2010, Vermont experienced a storm that turned into a nightmare for crews trying to clear the roads. First it snowed, then it rained, then more snow fell, heavier and harder. In the evening, temperatures plunged to the low single digits and stayed there for two days.
“Think of it as a baseball game with Mother Nature pitching,” wrote Gil Newbury, a district administrator with Vermont’s Agency of Transportation, in an e-mail. “The roads are wet and all the salt is washed off—strike one. Dump lots of wet, heavy snow on the road right at commuting time and let the traffic pack it onto the road until it turns to ice—strike two. Then drop the temperatures so low that salt and salt brine do not work—strike three.”
The brine VTrans used in some areas during the storm was a blend of salt and water, mixed with a small amount of Ice-B-Gone, a popular liquid magnesium chloride product. The brine has an oatmeal consistency, which helps it stick to roads. But to drivers, it looks different. And when multiple cars began sliding off roads, particularly on one stretch of road where brine had been applied extensively, fingers were pointed—at the brine and at VTrans. A rumor went around that the brine had been mixed incorrectly, leading to the driving conditions. Newbury denied a bad mix was the problem.
“The brine sure didn’t cause the problem,” Newbury wrote, “but we were a little short on being able to fix the problem as quickly with the brine as we would have liked. That’s an infrastructure challenge we are working to correct as I write.
“The bottom line is that there are times where Mother Nature is going to win despite all efforts, technology and expectations. The best hitters in baseball fail 70 percent of the time, and so will we at times. None of us were happy about that particular storm, but we did learn some good lessons and are already correcting our weaknesses for the next time.”
Behavior Matters
With all the talk about new technologies and treatments, it is easy to overlook what would be the least expensive, most effective way to improve safety on winter roads while reducing impacts from chemical applications—slow down. States have undertaken outreach campaigns to get this message out, but the message gets mixed when drivers see multiple salt-spreading trucks teaming up in a choreographed attack on a highway.
“If you’re maintaining the roads for high-speed traffic,” NH DES’s Williams said, “and at the same time asking people to drive slower, it doesn’t add up.”
To send a coordinated message, therefore, would require that highway agencies ease off on the deicing pedal, no easy feat.
“As little as 50 years ago, deicing materials weren’t used, and when it snowed people expected to drive in snowy conditions on snow-packed roads,” VTrans’s John Narowski said. “Obviously things have changed over the years, and our culture’s expectations are a lot more demanding. That’s a hard one to counter.”
Those expectations are everywhere, even in Canada, where the nation’s environmental agency has taken a highly publicized stance, labeling chloride salts as toxic and warning of their effect on the environment and biological diversity. At the request of Ontario’s environmental ministry, the University of Waterloo’s Mike Stone evaluated the effectiveness of Canada’s voluntary road salt management programs. He discovered during a workshop with winter maintenance managers that the push to cut back on salt was being imperiled by driver demands.
“People expect in the middle of February to get in their car, jump on the 401, the major highway here, and drive to Toronto at 120, 150 kilometers an hour [75, 93 mph], even if it’s snowing and they’re in a blizzard,” Stone said. “So people are putting a lot of pressure on the road authorities. In the workshop, they were saying, ‘Well, wait a minute, we don’t want to be liable, and we don’t want to have people phoning us all the time, so we put more salt on than is appropriate.’ So not only do we have to train private contractors, and continue to train and upgrade municipal individuals and provide them with better technology, we need to educate the public so they better understand the demands placed on road authorities and the potential implications of road salting.”
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The Dry Look Expectations from today’s drivers for clear roads in even the worst winter weather put pressure on road authorities to treat roads to a degree beyond what is necessary for basic safe travel. Measures such as mandatory snow tires and lower speed limits in bad weather would reduce the need for treatment, but are difficult to impose. |
During the salt reduction workgroup meetings in New Hampshire leading up to the development of the TMDLs, participants discussed a wide range of ways to use less road salt and achieve chloride reductions, including lower speed limits during storms, a greater willingness from school districts to declare snow days, and even passing a law requiring all drivers to take a winter weather driving course. All interesting ideas, but they never made it beyond the discussion stage. The idea of making snow tires mandatory also came up, and were that to happen, New Hampshire would not be the first. In Quebec, snow tires already are required, as they are in Sweden. The problem with a snow tire rule is the same as with a requirement telling everyone to stay home when it snows. Just as not everybody can telecommute, not everyone can afford a new set of snow tires.
Considering 75 percent of Americans drive to work, and most expect to drive fast regardless of conditions, it is hard to imagine environmental arguments about the risks of road salt having much impact on driver behavior. But drivers may be more open to the green pitch than expected. During the New Hampshire TMDL process, Plymouth State University conducted focus group discussions with drivers in Windham and Concord; the university reported the single most dominant message emerging from the focus group talks was that the driving public is willing to receive information from the state regarding the environmental impacts of road salt, and using that information, may be willing to change driving habits.
The Cary Institute’s Gene Likens also found evidence that environmental messages carry surprising weight during his studies at Mirror Lake. When a small road serving a housing development near the lake was paved in 2005, Likens anticipated an increase in sand and salt application. Figuring it was worth a shot, Likens talked to the road manager about the impacts of salt inputs to the lake. If the manager had been planning to use more salt and sand, the talk with Likens changed his mind. The anticipated increases never happened.
“I think we definitely underestimate the potential to respond to environmental messages,” Likens said. “Communication can go a long way, you know. Rather than yelling at somebody, talk to them.”
Looking Ahead
To outside observers of the work on winter road maintenance in recent years, it can appear that despite all the effort, we are no closer to a solution that satisfies all parties than we ever were. But appearances can be deceiving. Progress is happening. It is just not happening all at once, nor necessarily should it be.
“The knee-jerk reaction on a lot of this stuff is to say the problem is too big, it’s too expensive, we don’t know how to tackle it, so let’s do nothing,” EPA’s Silva said. “We’ve seen a lot of things come down the road in environmental protection over the last 35 years since the Clean Water Act was passed that all looked impossible at the outset. Then we’ve figured out how to address them by phasing things in, doing one piece of the pie at a time.”
The lessons learned from the TMDL process in New Hampshire are already proving to be helpful to other states as they move toward possibly developing their own chloride TMDLs. In Massachusetts, EPA’s Doug Heath is out in the field again, sampling for salt impacts to six streams and two water supplies in the area of proposed lane additions to Interstate 93. In Vermont, transportation officials are awaiting a final draft of a U.S. Geological Survey salt impact study triggered by plans to finally complete the Chittenden County Circumferential Highway. And in Connecticut, where a major expansion of Interstate 95 has been proposed, USGS is monitoring four stream locations for sodium and chloride counts to establish a baseline for comparison to the loads expected from the widened highway.
Head to Pelham, N.H., and you find another example of promising activity. This past December, the town became home to New Hampshire’s first porous asphalt road, thanks to a partnership of the University of New Hampshire Stormwater Center, developers, contractors, and Pelham officials. Porous asphalt, which lets stormwater drain through the road rather than pooling on the surface, now covers 900 feet of a road as well as driveways and sidewalks in a new Pelham condominium complex. Research at the UNH Stormwater Center has shown the permeability of porous pavements means 75 percent less salt than normal needs to be applied to a snowy surface to provide the grip drivers need. The porous structure provides a different route for sodium and chloride to pass through to groundwater, so such installations are unlikely near water supply wells. And widespread adoption on highways is doubtful given the expense of replacing existing surfaces. But on parking lots, where so much sodium chloride is applied, porous pavements provide one way to cut back on salt use. That is the kind of progress the stormwater center has been advocating for years.
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Easy on the Salt An adult community in Pelham, N.H., now boasts the state’s first porous asphalt road. Research conducted by the University of New Hampshire Stormwater Center shows porous pavements require less salt for winter deicing than do typical road surfaces. Photo by Robert Roseen, UNH Stormwater Center |
“We’re not saying ‘no more development’,” said Tom Ballestero, the UNH Stormwater Center’s principal investigator and lead scientist, and a NEIWPCC Commissioner. “What we’re saying is that it would be nice if we could make whatever we do be hydrologically transparent. That is, the water we send to our receiving streams is no different, in quantity and quality, than if we had never done development. That’s the Holy Grail. That’s what we are after. One way of achieving that with salt is by trying to use less of it.”
Whether all the focus on ways to use less road salt and minimize its impact on the environment is part of a trend that will end in the abandonment of sodium chloride as a deicer is remote. Among practitioners of winter road maintenance, salt remains the treatment of choice by a wide margin, and the factors that propelled it to that position remain in place. For more than 60 years, road salt has been poured on snowy roads and parking lots. Will it still be in use 60 years from now? On that question, Massachusetts Highway Division’s Tom Loughlin felt no need to elaborate.
“Yes,” was Loughlin’s unvarnished reply.
Except for those well outside the current of the environmental mainstream, nobody is really pushing for a total termination of salt use anyway. Not even the folks in Boxford.
“I don’t want to get into an argument with people about whether public safety on the highway is more important than drinking water,” Eisenberg said. “That is a no-win argument. What I say is leave the salt barn there, and put in a public water supply for the houses that are adjacent to the highway, and we can coexist together.”
The edge in Eisenberg’s voice ebbed slightly before he spoke again.
“But you know,” he said, “these are not easy issues both for the town or the state.”
Few would dispute him on that point.
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