The Vaisala Surface Patrol Dewpoint and Pavement Temperature Sensor DSP211 is an advanced mobile weather sensor capable of providing pavement temperature, air temperature, relative humidity and dew point readings - all while on the move. The Surface Patrol HD is used to detect possible freezing temperatures on the pavement. It assists maintenance personnel in determining when conditions are favorable for the formation of frost or black ice on roadways and can possibly indicate when precipitation is about to begin. The Surface Patrol HD provides comprehensive road weather data in a vehicle for real-time decisions. If your vehicles are equipped with mobile data collection, Surface Patrol HD will significantly increase your road weather network.