［Purposes ］ To address the difficulties in predicting localized fog on smart expressways and ensure driving safety in low -visibility environments，an intelligent guidance and warning system was developed to enhance proactive road safety prevention and control capabilities under adverse weather conditions.［Methods］ A closed -loop intelligent management and control system was built based on LoRa wide -area Internet of Things （IoT） technology，featuring “monitoring，warning，and guidance”.A gradient control strategy was adopted to deploy visibility meters，temperature and humidity sensors，and machine vision equipment.A low -latency LoRa communication network was constructed by fusing multi -source data，and real -time perception of localized fog hazards and multi -level response were achieved through an AI control center.［Findings］ Field tests demonstrate that with the intelligent guidance and warning system activated，the average emergency braking frequency in low -visibility sections （visibility of less than 200 m） decreases by about 72%，and accident response time is shortened to within 30 seconds.［Conclusions ］ Through dynamic guidance and warnings and multi -source perception synergy，this system significantly improves highway safety in adverse weather.It provides a replicable proactive safety prevention and control solution for smart expressway construction with substantial engineering value.