Development of a Risk Assessment Method for Life Safety in Case of Fire in Rail Tunnels

Abstract

The present paper describes the development of a risk assessment methodology to quantify the life safety risk for people present in a rail tunnel in the context of the creation of a fire safety design. A bow-tie structure represents the risk assessment model, starting from major contributing factors leading to disastrous events. Using past accidents for the construction of the event tree part of the bow-tie, the most important factors are determined to be: human behaviour; fire growth; ventilation conditions; safety system (e.g. Smoke & Heat Exhaust, detection, voice communication, etc.); population density. These factors are incorporated into the event tree using pathway factors. Frequencies are calculated for each branch outcome based on data from research projects, fault tree analysis and engineering judgement. For the determination of the consequences, the method makes use of three integrated models: the smoke spread, the evacuation and the consequence model. The models can take into account all types of geometry and materials, human behaviour and different susceptibilities of people for smoke. Together, they determine the possible number of fatalities, by means of an FID (Fractional Incapacitation Dose) value, in case of a fire in a rail tunnel. The final risk is presented by the expected number of fatalities, the individual risk and the societal risk. The societal risk is demonstrated by means of an FN-curve (Frequency/Number of Casualty-curve).

Interdependence of flows when merge in rail tunnel evacuations

“…Simulation models can provide consistent and accurate results when reliable inputs are used [2,3]. The potential of such analyses is clear [4,5,6,7]. Nevertheless, data on rail evacuation is scarce.…”

The Need for Hierarchies of Acceptance Criteria for Probabilistic Risk Assessments in Fire Engineering

“…Probabilistic Risk Assessment (PRA) is commonly accepted as one tool for PBD, as acknowledged by the fact that the UK guidance document PD 7974-7 is devoted to PRA for fire safety [5], by its inclusion in the SFPE Handbook of Fire Protection Engineering [49], by the many associated research projects in different fields of fire safety engineering (e.g. [3], [25], [30] and [70]), and by its identification as a research priority by the FORUM of Fire Research Directors [13].…”

A Novel Method for Risk Assessment of Cable Fires in Utility Tunnel

“…Finally, the heat release rate and toxicity of combustion products, smoke yield, and flashover category assess the effect of the mutual spacing between the cables and thermal conductivity of cable materials on fire risk [15]. Van Weyenberge et al [16] used smoke spread, evacuation, and consequence model to determine final consequences, and the final risk was given by the expected number of fatalities, individual risk, and societal risk. e aforementioned studies provide a basis to examine utility tunnel cable fires.…”