The problems of erosion and scour at bridge piers caused by runoff fivers have led to an alternative strengthening method. The strengthening method proposed is a process of modernization of bridges by arches with tight hangers - verticals and network. The present paper describes the behavior of the strengthening method at constructions's stage and later on the structural performance of the strengthening bridge in service. The method is applied to an existing bridge in Chile. It also validates the structural strengthening technique and establishes recommendations for its practical implementation.