Spreaders lay down salt repeatedly during the icy season. Sometimes they may throw down more rock salt on areas that already carry far more than the optimum 15 grams per square meter; at other times, they may not drop enough. The Salt Institute says that roads departments could cut their salt requirements in half through careful controls.
Accurate, real-time measurement of the amount of residual salt on the pavement is vital to maintaining safety and reducing both direct costs and collateral mayhem. There are already sensors that collect water splashed back by a salt truck’s wheels and measure the changes in refractive index that accompany increasing salinity. These systems, first described a decade ago, work well…if the road is wet.
In the current issue of Sensors and Actuators B: Chemical, engineers at Spain’s Universidad Carlos III de Madrid demonstrate a simple, robust optical sensor that can strap onto a bumper and measure dry-pavement salt levels as the truck drives over dry pavement.
via IEEE Spectrum
Image: Tom Gralish/The Philadelphia Inquirer/AP Photo
