Abstract: A Structures Assessment Methodology is presented, complementary to the Visual Inspection, which allows, through on-site non-destructive testing (NDT), to deliver a comprehensive quantitative evaluation of the "Structural Health" of the different elements. This allows essential information to adjust maintenance cycles or make timely based decisions in critical situations to guarantee future performance. The proposed methodology considers the execution of NDT to determine the state of the reinforcement, the characteristics of the concrete cover, and the presence of cracks. By extracting smaller size (1") cores, the ingress of carbonation or chlorides is determined. The results measured on-site are weighted to determine a Deterioration Index, DI. The aggressiveness of the environment is included through an Environmental Exposure Index, EEI. The incorporation of the results to the CTK-ConDiag® Model allows the combination of both indices, obtaining a Structure Global Deterioration Level SGDL, which measures the degree of damage determined at six levels. The proposed methodology is presented with the results of the study carried out on two specific bridges in Chile under different climatic conditions.