The New Guidelines of Italian Ministry of Infrastructures for the Structural Risk Classification of Existing Bridges: Genesis, Examples of Application and Practical Considerations

Bridges are crucial elements in the transportation networks. The failure of one of these structures causes generally important economic and social consequences on the whole road network. However, the current state of preservation of bridges and the recent collapses happened in the Italian territory shows that the level of attention of the stakeholders and managers on these structures was not sufficiently high. However, the numerosity of the existing bridges, the variety in terms of geometrical and material characteristics together with the limited technical and financial resources make impossible to analyze in a suitable amount of time all the bridges present in the Italian territory. With the aim of overcoming such difficulties, the Italian Ministry of Infrastructures and Transport (MIT) published unified guidelines for the classification and the risk management, safety evaluation and monitoring of existing bridges. The guidelines propose a multi-level approach, organized in different levels of analysis. To each level corresponds an increasing level of commitment, in both economic and technical terms, for the knowledge of the structures and of the aspects influencing the possible sources of risk. The paper illustrates the multilevel approach for the classification of the existing bridges proposed by the ministerial guidelines and presents and discuss all the background information and methods adopted to develop this multilevel classification