by Matt Mann, Research Program Coordinator
A major goal of winter maintenance is keeping the rods free from ice/snow. There is pre-storm preparation and then there is maintaining the roads, in safe conditions, during and after a weather event. The factors that agencies take into consideration when trying to achieve this goal range from available staff, application rates anti-ice and de-ice material, temperature, and impact on fleet etc. Among the various solutions, generally, salt is used during a weather event, based on its effective de-icing capabilities; also, it’s easy to handle, store and apply. Some negative qualities of road salt include: its effectiveness decreases dramatically at 15 degrees and less, it is highly corrosive, it does not stay on the road as much, and it can be costly.
Along with road salt, other winter road products include a number of liquid solutions and/or treated salt. Some liquid solutions and their qualities include:
- Calcium Chloride (CaCl) – highly corrosive, freezes at -15 degrees
- Magnesium Chloride (MgCl) – less corrosive (safe around plants/animals), freezes at -20 degrees
- “Ice Be Gone”/Magic Minus Zero – non-corrosive, freezes at -40 degrees and is EPA approved
- Caliper M-1000 & 2000 – non-corrosive, freezes at -85 degrees, good for pre-wet
Another alternative for regular road salt is to treat it. Some options for treated salt are Magic Salt, Fire Road and Clear Lane. All of these are less corrosive than regular salt. Also, when salt is treated, up to 90% stays on the road; where-as un-treated salt, only 60% stays on the road.
Most of the liquids mentioned above can also be used on gravel roads as dust control as well; this adds additional stabilization for the road and prevents loss of gravel over the years. The costs of these liquids solutions range from MgCl being the cheapest to “Ice Be Gone” being the more expensive one. In the middle is Caliper M-100 and M-2000.
Currently MassDOT pre-treats the state highways with a salt brine, and pre-wets their roads with MgCl. They are able to get a jump on most weather events by using pavement temperatures sensors and the Roadway Weather Information Stations (RWIS). Speaking with Paul Brown, District 1, MassDOT, “Most new trucks are equipped with pavement temperature sensors.” MassDOT also fully utilizes the RWIS, which measure real-time atmospheric parameters, pavement conditions, water level conditions, and visibility.