Key areas and rearrangement of the workflow for the evaluation of the landslide class of attention parameters of existing bridges

According to the new Italian Guidelines on existing bridges (LLG) the landslide hazard is one of the hazards that should be evaluated during the expeditious/quick Periodic Field Survey. Its assessment implies to estimate the landslide susceptibility, vulnerability and exposure based on primary (activity, velocity, and magnitude) and secondary parameters (extent of the interference, presence/absence of mitigation measures and overall reliability of the assessment). Unfortunately, in the LLG the extent of the areas that should be investigated is not clearly defined. Moreover, based on the work (i.e., application and testing of the LLG and compilation of the Field Sheet Form) of the Authors and other FABRE Consortium members on about 500 existing bridges, some gaps in the LLG and some uncertainties in the current workflow for collecting the data during the Periodic Field Survey, have been identified. Thus, the first aim of this work is to define the key areas that should be investigated for collecting the remote and ground data required for characterizing the geomorphological and the geological context and for evaluating the landslide susceptibility, vulnerability, and exposure, and hence the Landslide Class of Attention. The Diagnostic Area and the Geomorphological Significative Area mainly permit to characterize the geomorphological and the geological context and the proneness of the Geomorphological Significative Area and of the Relevant Area to generate Potential Landslide. The Geomorphological Significative Area and the Relevant Area mainly permit to identify and characterize both Recognized and Potential Landslides and accurately assess the parameters required for the evaluation of the Landslide Class of Attention. The second aim is to suggest the rearrangement of the workflow in order to overcome some uncertainties of the LLG, and to obtain a more accurate evaluation of primary and secondary parameters. Furthermore, the here rearranged workflow will support the technical staff involved in the Periodic Field Survey saving time and facilitating the collection of remote and ground data needed to compile the Field Sheet Form and to populate the database in a more adequate and functional manner.