tions of the experiments are presented in [Table 1](#pone.0201732.t001){ref-type="table"}. In experiment 0, participants were asked to evacuate from the tunnel. In experiment 1, the participants did receive any instructions as to the purpose of the experiment, suggested behavior in case of smoke, tunnel infrastructure or bus position in the tunnel. The bus was driven into the tunnel without stopping, in order to ensure an element of surprise for participants. In this experiment the bus stopped in the middle of the tunnel, just like in experiments 2 and 3. Detailed experiment setup is presented in [Fig 2](#pone.0201732.g002){ref-type="fig"}.

![Experiment configuration.\
Bus with participants were stopped in the left lane, in the middle between the second and third evacuation tunnel entrance. Smoke generators were located in front of the bus. Please note, that in order to improve readability of this figure we use different vertical and horizontal scaling. Due to the same reasons, the size of the bus is out of scale. All dimensions are listed in millimeters \[mm\].](pone.0201732.g002){#pone.0201732.g002}

The signs for the participants to start evacuating are similar to these which occur in a real accident including: presence of smoke, activation of the emergency procedures in the tunnel such as voice communications and emergency lights. Note that there was no special start signal from the organizers and the bus driver was instructed to stay in his place and not to give any prompts to participants, except the opening middle doors, when he heard the voice alarm.

The following experiments were carried out in almost the same manner with some variations. In experiment 2, students received instructions as to how to behave and were given safety rules in the event of a fire, which can be seen in appendix A. In experiment 3 participants were challenged to evacuate as quickly as possible. Finally, in experiment 4, the bus stopping place moved to a different position in the tunnel, as shown in [Fig 2](#pone.0201732.g002){re