Assessment of existing bridges: difficulties and challenges following the Italian experience

Many Italian bridges were built more than 50 years ago and are subjected to significant phenomena of deterioration that in some cases, especially in presence of hidden structural defects due to design or construction errors, have triggered catastrophic collapses. The current situation would require in-depth analyses to be carried out on all infrastructures to assess the current level of safety, according to in-force national standard, and to define appropriate construction or operational interventions. However, taking account of the large number of infrastructures, the necessity to define the priorities for detailed assessments arises and, this is why the recent Italian ‘Guidelines for risk classification and management, safety assessment and structural health monitoring of existing bridges’ includes, for the first time in Italy, a stepwise approach with increasing level of detail. In this article the main difficulties and limitations arisen in recent assessments of existing bridges according to these guidelines are discussed. The aim is to highlight either if they can be solved e.g. by improving the guidelines and/or the current codes of practice, or if they should be taken into account when setting the acceptable level of risk and the relevant assessment and rehabilitation requirements.