In the curve part of the route with insufficient sight distance, at the very small curve radius of the road in the mountain area, at the intersection with poor visibility (especially at the intersection without signal), at the railway crossing, etc., in order to help the driver, the pedestrians can identify clearly the ruts with limited visibility and prevent accidents, the road reflectors are set up. It is not necessary to set up reflectors according to the geometric alignment requirements of the road, but in fact, the visibility is extremely bad, and it is necessary to set up reflectors in such places. There was a time when the image reflected by the anti-glare mirror was different from the actual sense of distance. There was a discussion about whether it was necessary to set up road reflectors. Reflectors can reflect the vehicles or pedestrians on the other side, and since the setting of reflectors on the road itself has the effect of preventing accidents, it should be set at necessary places.