Bott's dots
noun [ plural ] US uk/ˌbɒts ˈdɒts/ us/ˌbɑːts ˈdɑːts/
圆形道钉，圆形路标石（大型道路上的圆形塑料或金属凸起，用以标示行车线或道路边缘）
small round raised pieces of plastic or metal placed along the lines on the surface of a large road to help mark the lanes (= separate strips of road for vehicles to drive along) or the edge of the road
Compare: reflectors rumble strip