The tragic accident in Crans-Montana, Switzerland, brings our attention back to a topic of great importance: the fire safety. In particular, in this article, we are going to see how engineering can be useful for forensic analysis – that is, how engineering helps investigators to reconstruct what happened and determine any responsibilities.
What is forensic engineering for: the autopsy of the disaster
When it comes to risk, particularly relating to fires, we know that there are a whole series of regulations, especially technical ones, which prescribe requirements, minimum standards, and characteristics that structures and environments must respect in order to guarantee that the effect of a possible fire is manageable. In particular, it is necessary to ensure that the response of the structure and materials is predictable, ensuring that necessary and sufficient time to allow people to leave the site of the fire.
Forensic engineering allows, through calculation models, analyzes carried out on the site of the disaster, and laboratory analyses, to reconstruct how it was possible for a simple spark to have triggered such a lethal fire. It therefore seems obvious that forensic engineering acts, in fact, as a tool to help investigators, the judiciary first and foremost, to establish whether the prevention criteria were actually respected within, in this case, the premises and who is responsible for any negligence and omissions.
Scene analysis: the 4 fundamental phases
Forensic engineering allows you to analyze a place where a fire has broken out, through four phases.
The first phase concerns the analysis and survey of the scene (Evidence Collection). First of all, a damage patternwe then study the traces left by the flames which usually leave V-shaped signs and the tip of this V indicates, in most cases, the area of origin.
The second phase concerns the sample collectionin order to determine the presence of any accelerants, such as petrol, alcohol, but also other materials capable of increasing the speed of spread of the fire from the point of initiation. We then proceed with the reconstruction of the pre-fire environments, therefore analyzing projects, plans, and any other source capable of attesting what the environment was like before the disaster. It is also conducted at this stage an analysis of the chronology of events (Timeline) in order to construct how events happened. The trigger point, cause, propagation time and flashover are then determined.
The third phase concerns the fire modeling and simulation (Back Analysis). In this phase, the fire is reconstructed through the use of specific software, thus comparing the reconstruction with the elements and above all with the damage present at the site of the fire, in order to verify whether or not what has been deduced in the first two phases corresponds to reality.
The fourth and final phase concerns the drafting of a final technical reportin which the forensic engineer is asked to answer a series of questions posed by the judge. In this case the questions are related to the compliance of the materials used in the construction of the structure, or the environment, to the technical regulatory requirements and whether or not the environments were organized in order to manage a fire in total safety, allowing people to escape without difficulty.
