U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
|Accelerating Infrastructure Innovations|
Publication Number: FHWA-SA-97-021
Date: March 1997
Conventional winter maintenance strategies involve waiting for the snow to start falling and then deploying plows and salt trucks to clear the pavement of snow and ice. These strategies produce safe travel conditions, but give the storm the upper hand.
Today, however, highway agencies have a new set of tools and strategies for keeping roads clear. These tools and strategies, which were evaluated and enhanced under the Strategic Highway Research Program (SHRP), stress a more proactive approach-for example, trapping snow so that it doesn't blow onto the road and implementing anti-icing strategies, which involve applying deicing chemicals before the storm hits, so that snow and ice never get a chance to stick to the pavement.
The result is a win-win situation-motorists get safer travel conditions, and highway agencies use less salt, sand, and other materials-which is not only more economical but better for the environment. Crews can also be more efficiently scheduled, minimizing expensive overtime and standby costs.
The Texas Transportation Institute (TTI) analysis concentrated on assessing the benefits versus costs of implementing an anti-icing strategy employing a road weather information system (RWIS). To be effective, anti-icing strategies require accurate, real-time information on pavement and weather conditions. Until recently, such information was not available, making anti-icing strategies difficult to implement on a broad scale. Now, however, this information can be easily collected with RWIS. Pavement and atmospheric sensors at each RWIS station monitor weather and road conditions; coupled with improved forecasting systems, these sensors give winter maintenance managers the information they need to determine where-and when-to apply chemicals to prevent snow and ice from bonding to the pavement.
According to the TTI study, highway agencies that adopt RWIS technology and switch to an anti-icing strategy can expect to reduce the amount of time that equipment and crews must spend on the road and the amount of salt, sand, and other materials needed to keep pavements clear of ice and packed snow.
Slightly more than half of the U.S. highway network is located in States hit by at least five winter storms every year. If the State and local highway agencies in these States were to immediately begin adopting anti-icing strategies, they could cut winter maintenance costs by almost $108 million per year. A more likely scenario, however, would be for implementation to begin gradually, with half or three-quarters of all highway agencies switching to anti-icing techniques over the next 20 years. Depending on the pace of implementation, TTI projects the total agency savings could range between $55 million and $81 million per year.
The magnitude of these savings means that highway agencies will quickly recover the $45 million spent to research, develop, and implement the SHRP winter maintenance products.
But even larger benefits will accrue to motorists who travel during winter storms. Because anti-icing strategies leave roads wet or slushy, instead of icy or snowpacked, TTI estimates that the number of accidents will drop dramatically, potentially saving highway users between $229 million and $447 million per year.
Highway agencies that are already implementing anti-icing technologies report savings that support TTI's predictions. For example, the anti-icing strategy in Boulder, Colorado, has resulted in a 55 percent reduction in sand use. When all costs are considered, the anti-icing strategy costs $1,600 per lane-km ($2,500 per lane-mi)-half the cost of the conventional sanding and deicing strategy.
Anti-icing techniques have other advantages. Because the Oregon Department of Transportation's (DOT) anti-icing strategy means much less sand is used, the highway agency is helping to minimize air and water pollution. And because it keeps roads clearer and safer, the anti-icing strategy has drawn praise from the State Police.
The RWIS networks that help make anti-icing strategies feasible also save highway agencies money:
To calculate the potential savings from the use of RWIS technology and anti-icing strategies, TTI used data collected as part of SHRP field trials between 1991 and 1993. According to the SHRP research, the average annual cost savings per mile per salt or sand truck route are:
Highway agency cost savings were calculated based on reductions in labor, vehicle operations, and materials resulting from fewer applications of salt, sand, and other materials needed during a storm.
The savings are partially offset by the cost of equipment needed to implement an anti-icing strategy.
Anti-icing materials are applied to a potentially treacherous winter road.
More detailed information on the benefits-versus-costs analysis of the SHRP products, as well as more than 100 case studies of how highway agencies are using those products, are available at the RoadSavers home page.