Models of risk assessment are a fundamental tool for defining strategies in the preservation process of archaeological heritage. As part of the author’s doctoral study, which focused on the survey as a tool for supporting this kind of procedure, a pre-existing experimental model for the local assessment of archaeological risk has been identified. Its prominent feature is the use of data describing the material composition and damage conditions of artifacts, derived from surveys and processed starting from their graphic rendering. Due to this peculiarity, the model was chosen as the basis of further research, structured through operational activities in the site of Villa Adriana in Tivoli and the concurrent reformulation of the algorithm, which is the core of the model. The paper discusses, particularly, the amending of some issues related to the interpretation of risk indexes as calculated in the model through the construction of an unambiguous semantic relation between graphic data derived from the survey, properly coded in 2D drawings, and numeric data processed in the algorithm. The renewed model became a solid base for further developments, mainly aimed at constructing a BIM-based data structure.