Tunnel Safety: The Human Perspective
The European project UPTUN (http://www.uptun.net/) focuses on all aspects of tunnel fire safety, with the aim to develop and promote innovative, sustainable and low-cost measures to limit the probability and consequences of fires in existing tunnels. In such as an approach, the human factor should also be taken into account, focusing on the tunnel user (car driver, train passenger), the tunnel operator and the emergency response teams.
What we learn from real accidents as well as from research and literature is that the human being does not always respond the way we want to. More specifically, people tend to underestimate the growing rate of fires (fires grow exponentially over time), so in case of a small fire people do not feel threatened and no action is undertaken until it can be too late (succumbing to smoke and heat). A selection from UPTUN studies shows that:
- The presence of other people affects the individual and results in group behaviour. As soon as someone reacts in a way that other people note, the behaviour spreads among a group. Unfortunately, this also holds for negative behaviour, such as staying in your car (for further information, contact boer@tm.tno.nl).
- There is a European leaflet telling people how to respond in case of accidents and incidents in tunnels. However, informing people beforehand in this manner is not sufficient; when confronted with a fire scenario, some people do not respond according to the leaflet?s instructions. Motorists need on-the-spot information from the operator, telling them how to respond, and most importantly why. It is important to get people to abandon existing mind-sets and adapt their behaviour to a new situation. We need to convince people to leave their vehicles, even if they are not fully aware (yet) of the danger. This underlines the criticality of early and effective public announcements.
- Information needs to be ?over-complete?, with if possible a repetition of the messages. Also, people with visible official status should be sent inside the tunnel to reinforce public address announcements and issue instructions to help people make the right decisions.
- A significant number of tunnel users forget to use the radio as an information channel.
- Wide, ?free-flowing? emergency exit designs should be located at frequent intervals throughout the tunnel. Also escapeways should be designed without steps.
- Auditory/speech guidance cues can be very effective under conditions of poor visibility, providing that the sound is self-explaining and it can be located in heavy smoke. The self-explaining sound beacon used in our studies helped participants (even without prior instruction) to go to the nearest emergency exit (this was observed to a far lesser degree in a previous test with a non self-explanatory sound beacon using broadband noise tones). The sound beacon also leads to higher walking speeds (boer@tm.tno.nl).
- A new evacuation system prototype was developed, with a highly visible flashing arrow pointing to the emergency direction and tactile guidance by means of a line one can hold (which moves you in the right direction). Because of an 'intelligent' programmable system design, the units can have their wayfinding direction reassigned individually or in blocks (for example to match tunnel ventilation sections or based on carbon monoxide readings from sensors within the evacuation beacons).These units can also be equipped with the sound guidance features noted above.
- The operator plays a crucial role in tunnel safety, with requirements to detect the developing incident and initiate emergency management plans at the earliest possible time. UPTUN has analysed the bottlenecks in the operator task. These bottlenecks can be overcome by looking carefully at recruitment, training and exercises, personnel and organisation and task support, and control and interface design. Since the operator is also a human being, he has to be helped to perform his tasks as well. It is essential that mistakes are registered, since only then we can learn from mistakes! It is also necessary for operators and rescue crews to be aware ofusers' perceptions about fire incidentsin tunnels and the way to deal with them.
- Critical attention should be paid to the communication procedures and facilities between the tunnel user, operator and the emergency rescue services. Only by proper co-operation, can the consequences of disasters be limited.
- Finally, training the rescuers (in the complete set of operator and tunnel user) is a must, both for a common safety culture and for a clear division of responsibilities on forehand in order not to lose valuable time at the time of the accident.
The UPTUN project runs for a further 2 years.
For further correspondence, please contact Marieke Martens at TNO (martens@tm.tno.nl)
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