Solar-powered system eases remote de-icing
Racine County, Wis., and the Wisconsin Department of Transportation (WisDOT) have installed a remote-controlled de-icing system on one of the state’s bridges. The ongoing pilot program is allowing WisDOT and the county to compare the system’s performance to traditional methods of controlling snow and ice.
Racine County primarily uses a truck-mounted spray unit to distribute magnesium chloride on its streets and bridges. However, the chemical is dispersed unevenly, depending on the speed of the truck. Additionally, the county cannot ensure timely chemical application on remote roads. Seeking a solution to both problems, the county joined with WisDOT and Energy Absorption Systems, a division of Chicago-based Quixote Transportation Safety, to test a remote-controlled system that dispenses a de-icing agent from a stationary position.
WisDOT and the county chose a remote bridge with a history of frost-related accidents as the test site. A general contractor installed FreezeFree Nitro, a solar-charged and battery- powered system that can be activated by a telephone call to a wireless paging device located in the system’s controller assembly. The system dispenses magnesium chloride through a sequence of spray nozzles pressurized with gaseous nitrogen.
In January 2001, WisDOT and the county began testing the de-icing system on the northbound portion of the divided bridge. They used the system until spring and repeated the tests the following winter. At the same time, they did not treat the southbound portion so they could determine how well the system worked.
“We found that, by using the system, we had less frost forming on the bridge deck and snow not bonding to the deck,” says Thomas Miller, area maintenance coordinator for WisDOT. “And, since the system can be activated anytime by pager, [we] save the cost of equipment and man-hours [used in manual application].”
WisDOT paid $1,000 toward the cost of the $26,000 system. Because the application was a pilot test, the manufacturer paid the remainder.
Once pilot tests were under way, the county took over the systemÕs operation and maintenance costs. It spends $22.50 each for two nitrogen bottles, which last throughout the snow season. It also spends $9 per month for the pager, and $0.58 per gallon of magnesium chloride. The system uses 415 gallons of magnesium chloride per season with two applications per week.
WisDOT and the county are continuing to test the system until they can gather information based on a typical winter season. (Last winter was mild so test results did not represent a typical winter, and, during the previous winter, the system was not used the full season.) They will compare the number of accidents occurring before the system was used to the number of accidents occurring while the system was used.