DULUTH, MN (KDAL) - Maintenance crews for the City of Duluth are making some progress in removing built up ice on the streets by using a more expensive calcium chloride-brine solution. In the frigid cold since last week's snow storm, regular salt has not been effective in melting the ice and crews have been using sand to improve traction. The city does not normally stock calcium chloride but was able to purchase a limited quantity and have been testing the solution on some selected icy streets and intersections. Although the calcium chloride works in sub zero temperatures, using it on all of the city's 400 miles of road would be cost prohibitive. It costs about 800 dollars per ton compared to the 64 dollars a ton for salt.