A novel fault tree analysis approach to investigate uncommon accidents in quarries: A case study

Quarrying companies are increasingly involved in developing effective Occupational Health and Safety Management Systems (OHSMS) to protect both their own staff and all those collaborating with their organization. The adoption of schemes such as BS OHSAS 18001:2007 helps the company to comply with legal requirements and serves the personnel both by raising awareness of the potential adverse consequences to which they are exposed (i.e., the risk of accident and potential occupational illness), and by limiting and managing the risk of occupational hazards. Since the quarry environment presents many hazardous factors, various approaches to monitor and control their effects are required; among them the choice of OHS risk assessment methods and the approach to accident investigation being the most crucial. This paper refers to a case study of an unusual accident which occurred in an Italian quarry recently. The analysis aims to identify and describe the true course of events, as well as to analyse the direct causes and contributing factors of the accident, the main objective being to identify best practices in risk reducing measures in order to prevent similar accidents occurring in the future. Initially a deductive approach is taken using the Fault Tree Analysis (FTA) method. This is then improved by integrating a Management Oversight and Risk Tree (MORT) technique and Multiple Cause Systems Oriented Incident Investigation (MCSOII). The proposed analysis is finally utilized to design and define procedures to manage these particular activities.