# A Methodological Framework for Bridge Surveillance
## 2 The Methodological Framework Proposed for Bridge Surveillance
Activity B, instead, involves the surveillance itself, in compliance with the mandatory regulatory context for the Assets that make up the infrastructure assets. In particular, the main goals of this plan are:  
* Inspections according to the new LG20 for all the infrastructure of MG3 (implementation of L1) within June 2023;
* Attention Class assessment for all the infrastructures of MG3 (implementation of L2) within June 2023;
* On-site inspections of the assets, conducted by specialized inspectors formed and coordinated by the CUGRI. The inspection and monitoring activities are implemented through an integrated operational model (Figure 5) aimed at guaranteeing the dynamic quality control of the in \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Macro Groups** & **Classification** & **Description** & **Quantity** \\ \hline
1 & Manholes and Tunnels (L \textless{} 6 m) & Manholes & 27 \\ \hline
2 & Bridges, Overpasses and & Bridge and & \\  & Underpasses (L \textless{} 6 m) & Underpass & 120 \\ \hline
3 & Bridges and Viaducts (L \textgreater{} 6 m) & Bridge and Viaduct & 207 \\ \hline
4 & Tunnels (L \textgreater{} 6 m) & Tunnels & 14 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Summary of classification, description, and quantity of the A3 highway assets for each macro group. section process, the congruence of the surveillance results' description, and the correctness and homogeneity of the interpretation related to the degradation phenomena observed. In particular, as regards the managing corporation, the involved resources are the Head of Surveillance (HS), the Contract Manager (CM), the Internal Inspectors (IT), and the Internal Staff offices (traffic-TO, mobility-MO, maintenance-MAO, etc.). As regards the CUGRI, the involved resources are the Legal Manager (LM), the Scientific Manager (SM), the Technical Contact (TC), the Scientific Contact (SC), the Inspectors (I), and the Contact person for safety aspects (CSA). The on-site activities are performed by four groups of inspectors (GI), each one composed of at least two to three inspectors and a group leader (GR), coordinated and reviewed by a group scientific manager (SR). The inspection activities are planned for each quarter, specified every two weeks by the scientific coordinator (CS). The overall process is subject to internal AUDIT activities shared by a Scientific Committee, made up of professors at the associated universities, with specific expertise in the field, and the managers of the managing corporation. All the results of the surveillance activities are managed by a BMS platform in order to allow the managing corporation to consult the state of conservation of the entire network in real-time. The BMS platform is part of the Information System (IS) of the CUGRI and is managed by a specialized technician (IT). The IS is also capable of collecting and representing monitoring data for the management of bridges and viaducts characterized by medium and medium-high Overall CdA. Figure 6 shows some screenshots of the CUGRI IS, in cloud format (right) and APP format, available for different types of devices. Figure 5: Operating model flow chart (for codes see text). Each bridge is georeferenced in a GIS platform and modeled in BIM, where each main component is represented in order to uniquely distinguish it. The BIM models of the bridges were developed with Autodesk REVIT software through a systematized procedure configured as an algorithm designed to simplify the entire process, called Scan-to-BIM [27]. It is a reverse-engineering methodology that employs a point cloud as the basis for the parametric modelling of the architectural asset. It can be organized into six sequential steps:  
* Three-dimensional survey (3 DS), consisting of an integrated Laser Scanning-Photogrammetric survey;
* Georeferencing (GEO);
* Federate modelling and Shared Coordinates setting (FSC), which represents the step when several sub-models are linked by georeferencing in a unified real-world coordinate system.