For excavation in sites often many firms proceed without effective and preventive estimates. The frequent accidents that occur indicate that we have not yet reached, especially in many sites of private clients, to a careful programming that allows reaching acceptable levels of security. The indications arising from the results of the inspections at construction sites and the reports drawn up following incidents highlight how often the work began without having first considered the factors potentially dangerous not only for workers but also for goods. The execution of the excavation by mechanical means or by hand requires an estimate of risk assessment process that, in addition to the specific characteristics of the site area, must consider the interference occurring with the conditions of the site and the neighboring areas (roads, presence of buildings, etc.) and the knowledge related to more general environmental context. The operating procedure, which has been initiate ted through some research undertaken in recent years by the "Mediterranea" University of Reggio Calabria is based on the comparison of experience in construction of knowledge. Through preventive observation (geological analysis, observations on morphological characters of area), project procedures that are being tested in some yards directly involving businesses and workers involved in specific processes.