The new Interstate 35W bridge spanning the Mississippi River in downtown Minneapolis has an anti-icing system that automatically sprays the road surface with corrosive chemicals in advance of a winter storm.

The new Interstate 35W bridge spanning the Mississippi River in downtown Minneapolis is a showcase of modern innovation. With 14-foot-wide shoulders, 10 traffic lanes and LED highway lighting, the structure also is light rail-ready to meet future transportation needs. But one feature of this “smart bridge” technology highlights a growing concern for the trucking industry: An automated system automatically sprays the road surface with anti-icing chemicals in advance of a winter storm, laying down a corrosive substance that literally eats away at trailers, brake systems and related components.

In the last several years, state departments of transportation across the country increasingly are switching from comparatively mild sodium chloride and salt brine applications to more effective yet more corrosive chemicals. The two most common options are magnesium chloride and calcium chloride.

What makes these chemicals so troublesome for fleets is their ability to wick into seams, cracks and paint chips and dry. When the chemical comes in contact with moisture, the chemical process begins; oxidation occurs within 24 hours and is visible in as little as three days.

“Where trucks and trailers used to last 10 to 15 years, now every time there is a nick in the paint and the metal is exposed to these chemicals, you run the chance of developing a huge mass of rust and corrosion,” says Al Anderson, director of national fleet accounts for Jost International. “When you have several hundred or thousands of trucks running around, that can quickly become expensive.”

Despite the corrosive effects of the chemicals on commercial vehicles, state DOTs’ primary objectives are to keep roads open and improve safety. “When roads get icy and cars start sliding around, it seems to us the better choice is to use chemicals that we know are effective while continuing to look for something that might replace them,” says Kevin Gutknecht, communications director for the Minnesota Department of Transportation.

As these chemicals become more prevalent nationwide, the trucking industry is left searching for answers. The increase in corrosion caused by these chemicals has become so pervasive that the American Trucking Associations’ Technology & Maintenance Council and other industry groups have formed committees and task forces to tackle the issue head on. “By the time our industry realized the problem, states were too engrained in using [the chemicals] and weren’t going to stop,” says Roy Gambrell, maintenance director for Nashville, Tenn.-based Truck It.

The trucking industry’s efforts gained some momentum with SAE J2721, a new recommended practice developed by the Society of Automotive Engineers Truck and Bus Corrosion Committee to address corrosion in commercial vehicle parts in favor of the traditional salt spray test from the American Society of Testing and Materials. J2721 mimics real-world applications with conditions including corrosive chemicals, drying, humidity and abrasive exposure. “When the chemical dries and starts to react with humidity is when corrosion begins to occur,” says Gambrell, who has been involved with TMC’s anti-corrosion initiative since its inception.