Bridge collapses are catastrophic events with countless consequences. However, bridge engineering has progressed thanks to the knowledge acquired analyzing collapsed structures. In this direction, modern forensic techniques allow detecting weaknesses and vulnerable zones in the structural systems. It has been demonstrated that the data related to bridge failures has been fundamental for engineers to propose and update theories, concepts, and designs in bridge engineering. This paper presents a methodology to analyze the initial damage and its propagation on steel truss bridges. The first part of the paper presents a comprehensive review of state-of-the-art and scientific challenges. The methodology is described in detail in the second part of the paper; it comprises two main tasks that are further divided into several activities. This methodology was developed as part of the Pont3 project and has proven to be of great value in gaining a better understanding of how progressive collapse occurs in steel truss bridges. By using this methodology, it is possible to detect initial damage and evaluate the structural behavior of steel truss bridges, which will ultimately lead to safer and more reliable structures.