Impressed Current Cathodic Protection (ICCP) is an electrochemical technique widely used, especially for repairing reinforced concrete structures contaminated with chlorides. This paper represents the results of the feedback of the ICCP system implemented on a road bridge, the Viaduct of Saint-Cloud in France. In 2012, a field trial was conducted in order to evaluate the effectiveness and the reliability of an ICCP system with embedded anodes designed for impressed current. The full-scale ICCP system was energized in 2018. Results of the four years monitoring including the variations of the applied current density and the polarization of the various anodic zones are presented. The ICCP data analysis is performed taking into consideration the initial degradation level of the span segments and the presence of prestressed tendons ducts. The electrical resistance of the circuit is influenced by several factors, the most important of which is the temperature. Considerations about the heterogeneity of the concrete resistivity are discussed.