Applications & Innovations
Better Roads Staff | April 5, 2012
On the Go Data
By Tina Grady Barbaccia
If you don’t like the weather, wait five minutes. How often do you hear that in parts of the country with, to say the least, unpredictable weather?
That unpredictability can create all sorts of headaches for municipalities and state Departments of Transportation when they’re trying to implement a winter maintenance plan or figuring out how many plow operators to deploy and where they need to go.
Use of sensors in a mobile weather system can help agencies get it right. Although using sensors to collect weather data isn’t a new idea, now road maintenance agencies can access the data from their entire network of roads with mobile sensor technology as they drive over it.
Mark DeVries, maintenance superintendent for the McHenry County Division of Transportation and APWA Winter Maintenance Chairman, says he believes mobile sensors will be very beneficial to anyone in the snow removal business. “This new mobile platform is virtually a mobile RWIS site [roadway weather information site], giving us all types of data across our roadway networks, airports or facilities,” DeVries tells Better Roads. “RWIS is one of our most valuable tools used in operations by the operating agencies and our forecasting services. Mobile systems will expand that benefit by gathering and sharing information across different topography and varying conditions.”
A mobile sensor technology data collection system developed by Vaisala enables road maintenance crews to gather pavement temperature, air temperature, road conditions and road friction levels from across the entire road network as they roll over it in pickups or work trucks. The data is collected using laser and infrared road friction observations from sensors mounted on maintenance vehicles. The data is collected in real-time from the sensors and then downloaded to a software program that provides recommendations to the winter maintenance supervisors about road treatment options.
The system is made up of three sensors. Each of them has been used in other formats on fixed stations. But the combination of the three using laser technology provides a look at the road to determine whether it’s dry, wet or carrying snow or ice. The road’s thickness is determined as well. By taking the road condition and the thickness of the road together, the sensors can calculate a value of friction or grip.
A road’s slipperiness is determined by a standardized scale, explains John Tarleton, roads marketing manager for Vaisala. The coefficient of friction to 1.0 is the roughest surface, and 0.0 is the slickest surface. A typical dry road is close to 0.8. “As moisture builds, whether it’s snow or ice, a dry road falls from 0.8 to 0.6 then to 0.4, which is considered ‘slushy,’” Tarleton explains. “At 0.2 or 0.3, a road is considered icy.”
The sensors help provide an actual number for road slickness for winter maintenance teams.
“You can see the actual friction level instead of just implied data,” Tarleton says. “The data can be submitted from a smartphone to a central website service so a supervisor can see the truck or any other patrol truck data via the Internet.”
In “snowbelt” areas, agencies use fixed weather stations, so conditions are already known in certain areas. But the areas in between may vary, and in locations where weather varies drastically — such as areas with valleys and mountains — mobile weather stations can prove useful. Fixed sites will always offer the 24/7 flow of data, and best accuracy over mobile sensors, Tarleton says. “But mobile sites offers a lower price point – and its mobile,” he says.
Tarleton is quick to point out that the mobile stations are not intended to – nor will they replace – fixed weather stations.
As much of the traveling public relies on technology to plan their trips, most of the Departments of Transportation (DOTs) are moving into a more technology-driven environment, says Annette M. Dunn, Winter Operations Administrator for the Iowa Department of Transportation and APWA Winter Maintenance Committee member. “Iowa DOT is beginning to develop, and rely on, more technology-driven decision-making tools. This type of mobile sensor information would assist us in our ongoing effort of winter efficiencies.”
John Scharffbillig, director of public works fleet services for the City of Minneapolis, notes that, “Technology is one of the tools that is being used by road crews around the country to deliver service for de-icing and anti-icing chemicals on roadways.”
For a case history on the Indiana Department of Transportation’s new salt storage facility and its decision to move from a traditional web truss structures to fabric buildings with rigid frame engineering go to www.betterroads.com and click on contributed case histories.