Interfering cranes (or secant cranes)
Tower crane features

Interference zones have evolved over the last twenty years. The first regulation was a circular issued by the Direction Générale du Travail on July 9, 1987, followed by a technical note dated March 6, 1991 concerning special safety measures for tower installations with interfering zones. As the level of safety of these devices improved, an informative annex dealing with them was adopted in the harmonized type C standard "tower cranes" ( NF EN 14439+A2 ).

When there is a risk of interference between cranes or overflight of dangerous areas on the site, safety devices are required. These may be "anti-collision devices" or "working space limiters". Both systems are referred to as "risk zone management devices".

The employer is responsible for implementing these rules of...