Just as a good meal can be ruined by too much table salt, too much sodium chloride applied to road surfaces to prevent icing can have a detrimental effect on vehicles, infrastructure and the environment. Engineers at Spain's Carlos III University (UC3M) have developed an optical sensor intended to prevent excessive salt treatment by detecting the amount of salt already on the road in real time.

Being based on weather forecasts, salting of roads is often carried out whether the road already has enough salt from previous applications or not. Marta Ruiz-Llata, a lecturer in the Department of Electronic Technology at UC3M points out that applying excess salt is not only wasteful, but has a corrosive effect on vehicles and infrastructure, damages vegetation and contaminates aquifers.

To prevent such excess salting, UC3M engineers developed an optical sensor that is able to detect concentrations of salt lower than 20 g/m2 – the quantity it is recommended not to exceed – by measuring salt's luminescence in response to exposure to UV light.

The engineers say the compact size and short response time of the sensor makes it suitable for mounting on road maintenance vehicles, which is something that is likely to occur in the not too distant future as the system's development was backed by ALVAC, S.A., a civil engineering company that has been in the road maintenance business for over 20 years.

The team is currently working on a system designed to monitor a number of road parameters and plans to integrate the salt sensor into that.

The optical sensor is detailed in a paper published in the journal Sensors and Actuators.