Warning markings for pedestrian and machine traffic
Vertical obstacles are not the only potential source of accidents. Horizontal obstacles, such as tripping hazards or falling edges, should also be marked accordingly. Practical tests have shown that safety signs placed close to the ground are more likely to be seen and therefore work much better than signs placed on the wall.
The combination of black and yellow serves as the classic warning colour combination for fixed and immovable obstacles, red and white for movable ones. Specifications for the marking of danger points and obstacles are provided by ASR A2.1 and ASR A1.3..