Sound signals to improve evacuation in road tunnels

Although visual signage is the most common means of evacuation support in road tunnel emergencies, these can be of little help when there is dense smoke product of a fire. In such cases, auditory messages can lead evacuees out of a tunnel even in conditions with limited vision. This paper presents the results of two full-scale experimental studies designed to evaluate whether sound signals can help people to evacuate out of a smoke-filled tunnel due to a fire. Experiment 1 tested two sound signals (i.e. clicking sound and whistling sound) and their effect in aiding evacuation from a tunnel with poor vision. Experiment 2 was based on the results from Experiment 1 and tested two sound signals (i.e. clicking sound and bell sound). Experiment 2 confirmed that the evacuation success rate increased as people received information that they should follow the sound. In addition, subjective assessments by the participants revealed a higher preference for the tone-based sounds (i.e. bell sound and whistling sound) over the clicking sound. The results of this study can have implications in the assessment of new measures to support a more efficient evacuation from tunnels during emergencies.