Timing Is Everything with Winter Maintenance
Pavement and weather sensors improve the timing—and thus the safety and cost-effectiveness—of winter maintenance operations.
The Challenge
Winter in South Dakota can be long and harsh, keeping maintenance supervisors busy monitoring winter weather and road conditions. Traditionally, the South Dakota Department of Transportation (DOT) relied on winter maintenance supervisors to inspect sites where snow problems and icy conditions are common. Experienced supervisors are excellent judges of what conditions to expect based on these inspections, but winter storms can bring different problems to different areas, making it difficult to decide where and when to dispatch plows and salt trucks.
To make winter maintenance more efficient and effective, the DOT decided to adopt road weather information system (RWIS) technology. The technology, evaluated under the Strategic Highway Research Program (SHRP), provides winter maintenance managers with constantly updated weather data, such as temperature and precipitation, pavement temperature and moisture data, and the amount of salt or other chemicals on the pavement.
Putting the Technology to the Test
In 1991, South Dakota DOT began installing RWIS units. The system now includes 34 units, including 2 operated by city governments and 3 operated by county governments. The DOT plans to add another 10 units over the next year.
The sensors are placed at sites that have historically experienced problems as a result of winter weather, such as bridges, as well as at locations far from maintenance offices and where the data collected by the sensors are useful to more than one maintenance unit.
By collecting extensive real-time information on prevailing conditions on South Dakota roads, the RWIS helps winter maintenance managers determine when and where to dispatch crews to plow or apply chemicals or sand. Each storm requires a unique response, and the RWIS data help make it possible to devise the right response.
"Our supervisors tell us they use the RWIS because of the variance of winter storm conditions—the frequency, duration, temperatures, and type of precipitation," says Norm Humphrey of South Dakota DOT. By responding with the best strategy for a particular storm, the DOT can keep roads safe for traffic.
Because RWIS data helps the South Dakota DOT call out the right equipment at the right time, the system saves the highway agency money. "Our biggest savings is probably from better scheduling of crews," Humphrey says. In addition, supervisors do fewer road condition inspections, saving time and money.
To reduce costs, the South Dakota DOT is beginning to evaluate anti-icing strategies. These strategies will incorporate the use of RWIS data to help determine when to apply chemicals to the road to prevent ice from sticking to it. Since preventing the ice-to-pavement bond requires less chemical than breaking the bond, the DOT is able to reduce its chemical use, thus saving money while keeping roads even safer.
The Benefits
Since implementing the RWIS, says Humphrey, "I think we're probably more timely. More timely means better safety, less material used, and lower costs. Timing is the key element and the biggest benefit of the system."
