Remote optical sensor for real-time residual salt monitoring on road surfaces

Spreading salt on roadways is the most cost-effective tool for preventing death, injury, and property damage from winter traffic accidents around the world. But it has been estimated that for every dollar spent on the salt itself, there may be three dollars in damage to roads, vehicles, and the environment, as salt eats away at bridge decks, corrodes rebar, blights neighboring vegetation, and drains off into surface and groundwater.

Spreading more salt on roadways that already have enough for safety wastes salt and money, and increases damage to the infrastructure and environment. For that reason, accurate and real-time measurement of the amount of residual salt on the pavement is vital to maintaining safety and reducing both direct costs and indirect environmental costs. This research demonstrate a simple, robust optical sensor that can be mounted on-board maintenance trucks and measure dry-pavement salt levels as the truck drives along entire stretches of roadways.