Human behaviour during an evacuation scenario in the sydney harbour tunnel

Tunnels evoke unique emotions and perceptions that may affect human behaviour in the event of an emergency. Limited empirical data on human factors affecting response during tunnel emergencies have constrained our ability to plan for these aspects of incident management. The Sydney Harbour Tunnel is Australia"s only immersed (subsea) road tunnel. It was the site of a recent observational study conducted to further develop tunnel evacuation procedures and systems. The event involved the evacuation of 32 volunteers from a controlled "burning car"scenario. Response data was obtained from film footage and a post-exercise questionnaire. Pre-recorded audio messages were found to be the predominant source of information used in forming the decision to evacuate, augmented by social information exchange or social "checking" processes. Participants demonstrated much indecision and did not commence evacuation until audio instructions were issued. Three quarters of participants made the decision to evacuate based on audio instructions, although 34 percent reported some difficulty hearing the audio and were more likely to make decisions based on the behaviours of others. After an initial period of evacuation "inertia", evacuation was initiated by those able to hear the audio instructions within seconds of the announcement and the evacuation was completed in just over two minutes. European and Australian studies suggest that rapid evacuation during such events may save lives. Findings from this field exercise indicate that expediting early decision-making to evacuate through improved communication (early loud clear audio messaging) is key.®.