Subjective individuals' perception during evacuation in road tunnels: Post-experiment survey results

The aim of the research was to analyse the process of evacuation from the point of view of the individual's perception, behaviour and decision making. The study used a survey method that was conducted during two real-scale evacuation experiments in real road tunnels under smoky conditions. All experiments, with fire scenarios and procedures were very similar to real accident. Respondents' observations and important aspects affecting the evacuation process were verified, including decision-making during evacuation, loss of bearing in smoky conditions and group evacuation. The results indicate that participants in the experiments had started the evacuation due to smoke in the tunnel and fire drill. The evacuees observed decreased visibility on the escape route as well as a loss of bearing in the tunnel when smoke levels were high (extinction coefficient Cs > 0,7 m-1). The participants in the experiment evacuated in a group (when the tunnel infrastructure was unknown and there was no instruction as to what to do) and in twos under the smokiest conditions (extinction coefficient Cs~1.0-1.1m-1). During the experiments, the large impact of herding behaviour and following the group was noticed. The results of such studies based on real-scale evacuation experiments in road tunnels are essential to improve the level of safety in the road tunnel. In the surveys, the participants pointed to important issues related to evacuation, which require particular attention during the design, implementation and acceptance of this type of construction. The results of the study provide a better understanding of the behaviour of evacuees and indicate areas where tunnel infrastructure needs to be improved.