Efficient and safe evacuation in case of fire in a tunnel is the main factor for the adequacy of the safety level. Due to the confined environment, accidents inside road tunnels, especially fires, can have dramatic consequences. To prevent this, it is essential to take into account the factors that hinder the evacuation process. The purpose of this study is to identify the possible optimal locations for escape routes (emergency exits) by studying the conditions in the environment of a road tunnel with and without natural ventilation during a fire. This will be achieved by studying the factors that affect users during evacuation process, temperature and toxicity tenability limits, which will be determined through the fractional effective dose (FED). By setting safe evacuation as those cases in which the above limits are not exceeded, the maximum distances of emergency exits were determined and compared with international standards and regulations. To complete the study, FDS (Fire Dynamic Simulator), a CFD (Computer Fluid Dynamics) model was used to simulate the fire propagation while Pathfinder, an agent-based computer model, was used to simulate the evacuation and determine the effects of fire on occupants. The results showed that the lack of visibility due to smoke propagation has a major impact on passenger behaviour, leading to a reduction in movement speed and, consequently, an increase in the required evacuation time. At the same time, it was observed that natural ventilation significantly affects the evacuation process, increasing the impact on users as the smoke covers the entire tunnel cross-section in a shorter period of time.
Karamalegkou et al. (Thu,) studied this question.