The Italian Guidelines on Risk Classification and Management of Bridges: Applications and Remarks on Large Scale Risk Assessments

Abstract

Bridges are essential for guaranteeing the functioning of transportation systems since their failure can cause serious threats to the safety, well-being and economy of modern communities, especially in emergency conditions. Following recent bridge failures, among which include the Morandi bridge in 2018, specific guidelines on risk classification and management, safety assessment and monitoring of existing bridges have been issued in Italy by the Minister of Infrastructure as a mandatory code. They pay particular attention to the evaluation of the residual life span of critical transportation infrastructure dating back to the 1950s and 1960s of the last century. Being a newly issued tool, the Guidelines need to be applied and tested in order to find possible drawbacks and to point out the main factors influencing their results. Therefore, in this study, after a short description of the Italian Guidelines, pointing out some differences with other approaches adopted worldwide, some advantages and disadvantages are discussed by an application to a bridge stock located in the Basilicata region (Italy). Data needed to apply the Guidelines are gathered by a purposely set up procedure that exploits existing databases on road infrastructure (OpenStreetMap) complemented by additional data retrieved by means of public image repositories (Google Street View). By accounting for the qualitative nature of the risk classification results obtained by applying the lower analysis levels of the Guidelines, a prioritization method is proposed for ranking bridges for higher assessment levels and possible interventions, as well as consequent funds allocation. The application shows that the Guidelines’ approach tends to provide conservative results. In fact, even in case of bridges with low degradation levels, the final risk classification induces actions undertaken for preliminary or detailed assessment; thus, normal operation (with periodic inspections) would not be possible anymore.

Risk Assessment of Terrestrial Transportation Infrastructures Exposed to Extreme Events

“…For instance, the Italian guidelines on risk classification and management of existing bridges group bridges into risk classes for prioritization of detailed assessment and funds allocation. Nevertheless, the application of the framework to real road networks has been found to provide conservative results and do not enable the ranking of bridges belonging to the same class given their qualitative nature [21]. Other risk assessment literature considers transport infrastructure specifically but treats the risk semi-quantitatively (e.g., [6,26]) and is focused on a specific hazard type (e.g., [27]) and/or a specific asset (e.g., [20]).…”

“…One of the main drivers of this problem is the lack of a systematic data collection procedure. Thus, some efforts have been made to propose protocolled taxonomy and methods for data collection, aiming at unifying databases into a functional structure ready to be used in risk assessment frameworks (e.g., [21,22]).…”

“…The available funds for operation, maintenance and climate adaptation measures are limited, and it is important to make well-founded priorities. Thus, risk-based approaches are increasingly being applied to aid in the decision-making process of planning maintenance and prioritizing risk mitigation measures [20][21][22]. Here, the main tasks are to identify the most vulnerable assets and prioritize measures and resources according to the available budget.…”

Application of the new Italian assessment guidelines to a 1960s prestressed concrete road bridge

“…The Italian road network is owned and managed by multiple entities, which means that precise figures on the number of road bridges are difficult to obtain. However, Santasiero et al 3 report that the number is approximately 120,000. From a short drive along the Italian highway network, one can readily observe that there is a diverse range of bridge typologies, built using varying construction materials and techniques.…”

Improvement of the Inspection Interval of Highway Bridges through Predictive Models of Deterioration

“…A successful Bridge management system (BMS) depends heavily on defining appropriate intervention actions to ensure structural safety, functionality, and durability while maintaining the lowest financial investment related to the available budget [1]. By accounting for an adequate quality control plan and a risk classification, a prolonged quality assurance of bridges can be assured and, consequently, a proper allocation of funds [2][3][4].…”