Rete Ferroviaria Italiana in its public role of Infrastructure Manager is responsible for the management and safety of rail operations for approximately 17’000 km of lines and therefore addresses several types of risks. Among natural hazards, seismic risk assumes an high relevance. In compliance with the Italian law OPCM 3274/2003 (Ordinance of Presidency of the Council of Ministers No. 3274, 2003) the seismic vulnerability of about 5600 bridges is currently being assessed with particular reference to strategic railway lines. The assessments concern, in the first instance, all structures that had been designed before 1984, year of the first seismic regulation published in Italy. The seismic mitigation risk process mainly consists in an initial phase of geotechnical and structural investigations aimed to conduct seismic vulnerability assessment of the existing infrastructures. If any critical aspects of structures have been identified, a seismic strengthening design is carried out in order to build interventions increasing the level of safety against seismic shocks in existing bridges.