As it moves across the sky, it will appear as though the tower is dancing. This is not just an optical illusion but also has real world effects. The crane's movement can affect wind conditions at the base of the tower and this, in turn, can influence the stability of the structure. In addition to being aesthetically unpleasant, the crane's oscillations are hazardous for workers at the site. They can lead to accidents by causing people to lose their balance and fall off the tower. The maximum safe working height for a crane operator is about 100 feet above ground level. Any higher and you start to enter dangerous territory where falling objects can cause serious injury or death. Crane operators must be highly trained professionals who know how to take care of themselves as well as others. They should never be allowed to work alone at any height. Towers with cranes are used for large infrastructure projects such as building bridges, dams, and highways. The weight of these structures needs to be supported by several hundred feet of cable attached to the tower.