The role of the Ministry of Culture in France, through the decentralized services that are the DRACs (regional archeology service), has many facets. From the act of prescription to the conservation solution, the RAS is at the heart of the equation: development project (destruction) - scientific problem - heritage protection (conservation). There are many links in the operating chain for the study of an urban project. What are the scientific choices? What is the prescription policy implemented in the case of a prehistoric site? Is it similar for all archaeological periods? What applications of the code du patrimoine? A comparative approach between Hauts-de-France’s and Île-de-France’s practices is therefore proposed.