The system is installed at intersections with no truncations where it is difficult to put up road signs and have problems such as narrow roads or poor sight distance. Intelligent detection technology is applied to detect oncoming traffic signals at arterial intersections and early warning LED signs on the branch roads (or opposite lanes) are activated through the IoT communication transmission system. The early warning signs will display the text message "Traffic coming from the side, drive with caution" as a reminder to passersby to slow down, stop and yield.