Abstract
Aim: To identify an evaluation process concerning the safety of road tunnel users during a fire incident. The study focussed on tunnels with longitudinal ventilation systems and examined safety from an evacuation perspective, utilizing numerical modelling tools.
Introduction: During a fire outbreak in road tunnels, the behaviour of users is critical, specifically during their individual attempts at rescue and evacuation. The outcome from such endeavours is dependent on a range of factors, including: tunnel geometry, safety systems in existence, ventilation, makeup of combustible material, heat release rate during burning and location of emergency exits. The use of numerical modelling tools is becoming an accepted norm, which, among others, is used to evaluate the effectiveness of safety systems as well as the safety of users during an evacuation. The latter is usually tested at the facility project design stage. Conduct of such activities require an individual to have detailed knowledge of a range of disciplines, thorough knowledge of mathematical modelling and application tools, awareness of software limitations, issues associated with computational fluid dynamics, specific knowledge concerning the behaviour of fires and appropriate selection of boundary conditions.
Methodology: This article reveals outcomes from a literary review of specialist material, including selected national and international project design guidelines derived from science and technology discussions, and numeric research performed in laboratory as well as real life conditions. Additionally, the paper presents original research results produced by the authors in the course of their ongoing activities at the Faculty of Mining and Geoengineering, at the AGH University of Science and Technology.
Conclusions: Computer numerical methods were harnessed to perform an assessment of safety in a fire environment, for users of road tunnels with longitudinal ventilated systems. This assessment was performed by applying a safe evacuation criterion, which requires identification of the start time when the critical environmental conditions occur in the tunnel, that is conditions presenting a hazard to the life and health of people who undertake self rescue activities, and duration of users evacuation to a safe location. The study identified essential assumptions, boundary parameters, specialist bibliography and analysis results from the work performed by the authors. Outcome from research indicates that in one-way road tunnels, of 1500 metres in length, without emergency exits or with exits spaced 500 metres apart, and ventilated by longitudinal systems, the required safety level will not be achieved during a fire incident with a heat release rate of 30 MW.
Keywords: fire safety, road tunnel, fire ventilation, longitudinal ventilation, evacuation
Type of article: review article