Automatic fog condition detection and alarm system and method for expressway

The invention discloses an automatic fog condition detection and alarm system for an expressway. The system consists of detection equipment and control equipment, wherein the detection equipment automatically detects fog condition information by transmitting/receiving code modulated infrared light and controls a light emitting diode (LED) alarm module to give an alarm signal; and the detection equipment detects the fog condition and simultaneously has a temperature and humidity information detection function; the system interconnection in the system is realized by a ZigBee wireless communication network; a large-range fog situation and small-range fog can be detected effectively, moreover, complex network layout is not required, and the structure is simple; the system communicates with the external by adopting general packet radio service (GPRS) or an Ethernet, so that a traffic management department can master the fog condition information and the temperature and humidity information of the expressway in time conveniently; and power consumption of the system is reduced to the maximum extent by adopting low-power consumption devices and a method of detecting periodically and sleeping at the rest of time. The system can be widely used for automatically detecting the fog condition of the expressway in real time, prewarning traffic safety, and guiding vehicles to pass safely.