Transparency vs magic numbers: The development of stair design requirements in the Italian Fire Safety Code

Practitioners may face difficulties in the interpretation of fire codes since they often present so called "magic numbers", i.e. numbers available in the codes which are listed for providing the design of building fire safety, for which the derivation and justification are not explained. The present paper discusses the need for a transparent regulatory approach, in which legislators publicly justify each of the choices made during the development of the fire codes. This approach has been used for the first time during the development of the Italian Fire Safety Code DM03/08/15, where the process adopted for the development of the code requirements has been publicly released in parallel with the code itself. This is deemed to facilitate the interpretation of the fire code, avoiding mis-use and preventing criticism on lack of transparency. To address this issue, the Italian legislators have conducted a process of reconstructing the assumptions adopted for the definition of magic numbers in other International codes (i.e., British Standard 9999) in order to identify suitable specifications for the national context under consideration. This includes the performance of a series of calculations rather than a mere historical examination of their basis. As a first attempt towards an increased transparency in fire code development at an International level, this paper publicly summarizes the process adopted by the Italian legislators for the development of the new Italian fire code, focusing on the exemplary case of the calculations performed for the definition of the requirements concerning stair design (i.e. vertical evacuation). This is presented by comparing the deemed-to-satisfy provisions of the Italian code with, the ones given in the British Standard 9999. The process of developing fire codes is discussed together with the benefits associated with transparency in the assumptions adopted for their definition.