The Idaho Transportation Department (ITD) has used an electronic spreader control system from Cirus Controls to help cut its winter maintenance spending by 29 percent over three years, and attributes the system to a drop in its three-year average of accidents on snowy and icy roads by 27 percent.
“Idaho’s success is largely based on the technology we used to support the Winter Performance Measurement System,” says Dennis Jensen, ITD mobility services-winter maintenance coordinator. “By upfitting our snowplow trucks with the SpreadSmart Rx electronic spreader control system from Cirus Controls and installing RWIS (road weather information system) sites throughout the state, ITD can now see exactly what treatment its snowplow trucks executed at RWIS locations and match that specific material application data and timing to the RWIS road surface data, before and after treatment, to evaluate the effectiveness of its winter road maintenance operations.”
The system, which has been installed on 288 of the agency’s 450 snowplow trucks, provides data on the amount and type of materials applied using GPS location data and “nearly” real-time reporting. It also helps “regulate the rate of salt and other deicing materials applied to road surfaces based on a snowplow truck’s speed, location and road surface temperature,” according Paul Mortell, CEO and founder of Cirus Controls.
ITD plants to install the system on its remaining trucks over the next two years.
The Winter Performance Measurement System is designed to measure how quickly the snow and/or ice surface is reduced and good traction is restored to the roadway surface. ITD developed a Winter Performance Index Report that uses the three indices of storm severity, mobility and performance to do this. They are calculated as follows:
- Storm Severity Index: Maximum wind speed plus the maximum layer or layers of ice, snow and/or water plus (300/minimum surface temperature.)
- Mobility Index: Percentage of time the road surface traction or grip is above 0.60 while there is precipitation on the roadway during freezing surface temperatures.
- Performance Index: Duration of time the roadway surface grip is below 0.60 divided by the storm severity index. It updates snowplow operators and winter maintenance managers on the effectiveness of deicing treatments applied to road surfaces by snowplow trucks.
There are 127 RWIS sites in Idaho that sample a wheel track on a road surface to measure layers of ice, snow and water in addition to the condition and temperature of the roadway surface as well as the air temperature, humidity, wind speed, precipitation and visibility. An algorithm is then used to determine the “grip coefficient” of the road surface, which is then used to calculate the mobility indec and performance index.
“An important benefit of the Winter Performance Measurement System and its Winter Performance Index Report is that ITD operators and managers have the data to evaluate each individual deicing treatment applied by snowplow trucks upfitted with electronic spreader controls and the ability to drill down to the effectiveness per lap,” Jensen says. “Our best practices will provide more consistent operations statewide and continue to cut winter maintenance costs and lower the number of accidents on winter roads by reducing adverse driving conditions.”