It is incorrect to assume that the same intervention techniques dedicated to superficial portion of the slopes can be applied for more deep seated instabilities.  Superficial instabilities result from alterations and deterioration of the rocks by plant action, thermal expansion, wind and salt erosion, excavation methods, cold and thaw processes, progressive weathering of joints within rocks, hydrostatic pressures, seismic action to name a few.  These problems are occasionally reduced to simple schemes.  Rather, quantitative assessment should be undertaken to adequately and efficiently quantify the risks associated with possible landslides for a particular slope or set of slopes.  The risk assessment should weigh up the probability, magnitude and distribution of occurrences against the unforeseen and undesirable consequence of human casualties, property damage and loss of service.  Risk management should focus on identifying key potential risk factors which are logically evaluated in terms of probabilities, costs and other benefits, so as to optimally manage the risk.

Rockfall protection systems have become a key element in the design and maintenance of infrastructure networks impacting directly on safety and necessitating thus, a new approach that encompasses the overall analysis of the rockfall structural system and not the individual components alone.  The word "system", best describes the different structural components that interact with one another.

A key distinction ought to be made between active and passive protection systems.