What is the white semicircular marking inside the circle?

[DeSienna]

It is a distance confirmation line. The distance between each semicircular marking is 30 cm, and they appear in continuous groups spaced 50 meters apart. When vehicles reach the distance confirmation line section, it is essential to maintain a safe distance from the vehicle ahead to avoid traffic accidents. Here is additional information: Slow down when passing distance confirmation lines: Vehicles must reduce speed and maintain sufficient distance from the vehicle in front to ensure driving safety and prevent accidents. Sections with distance confirmation lines are often accident-prone areas or locations where major traffic accidents have occurred, so extra caution is required. There are two types of distance confirmation lines: The first is the white zigzag distance confirmation line, and the second is the white semicircular distance confirmation line. Their purpose is the same, although the measurement methods differ. Both serve as safety warnings on the road to prevent traffic accidents while driving.