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Publication Number: FHWA-SA-96-016
Date: May 1996
If sand from winter maintenance operations is turning up in nearby bodies of water, what's the best response? For the Nevada Department of Transportation (DOT), the answer is to use less abrasives in the first place--a feat made possible by using a road weather information system (RWIS) coupled with an anti-icing strategy.
Concerned about excess sediment and nutrients in Lake Tahoe, the Lake Tahoe Regional Planning Agency mandated in 1995 that something be done about the runoff of sand from State Route 28, which borders the lake. Nevada DOT estimates that 70 percent of the sand is generated by snow and ice control operations. The sand is carried by rain and melting snow into culverts that drain into the lake.
To keep the sand out of the lake, Nevada DOT will spend almost $3 million to construct a series of catch basins and sand traps in the culverts along a 2.4-km (1.5-mi) stretch of Route 28 between Incline Village and Sand Harbor. But installing catch basins and traps along the entire length of the road is just not practical, from a budget standpoint. What was needed was a way to cut down on the use of abrasives in winter maintenance--the less sand applied to the road, the less threat to the environment.
Nevada DOT decided to apply anti-icing techniques to the roadways in the Lake Tahoe area. "Instead of collecting sand we put down, we just won't put it down in the first place," says Rick Nelson, district engineer for Nevada DOT. Because less sand will need to be collected, the DOT can stretch its dollars by building smaller traps and placing them further apart.
Nevada DOT began experimenting with anti-icing technologies in 1991, when it started using an RWIS, a technology evaluated as part of the Strategic Highway Research Program (SHRP). Using data from the RWIS, the DOT knows when and where to send crews to apply liquid deicing chemicals to the roads before an approaching storm hits. These chemicals prevent ice and snow from bonding to the pavement in the first place, making plowing easier or unnecessary and travel safer. Nevada currently uses magnesium chloride, but plans to switch to less-expensive sodium chloride brine.
By implementing anti-icing strategies, Nevada DOT uses considerably less deicing material than with conventional deicing strategies. It has cut its use of road salt in half and its use of sand by 70 percent--which means significantly less salt and sand end up in the lake.
Nelson also notes that less abrasives on the road mean less dust, and thus less air pollution.
"There's a continued benefit," Nelson says. "We don't have to clean up abrasives, we don't have air quality problems, we protect the water, and motorists get a clear road."
Nevada DOT is expanding its network of RWIS sites to cover an extended stretch of the Sierra Nevada range from Reno to Lake Tahoe and other locations.
For more information, contact Rick Nelson at 702-688-1250 (fax: 702-688-1189) or FHWA's Salim Nassif at 202-366-1557 (fax: 202-366-9981).
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