TRAVELLING further and deeper underground is increasingly a part of everyday life. There are now more than 180 tunnels over 1 kilometre long in Europe and hundreds more are planned. A 125-km rail tunnel between Taiwan and China is being planned, as is a 95-km railway under the Irish Sea between Dublin and Holyhead in Wales.
But how safe do we expect to be in these tunnels? And who鈥檚 deciding what safety precautions are needed? After all, not every tunnel builder can afford the 拢11 billion that was spent on the 53-km Channel Tunnel. That cash paid for a safety tunnel to make it easier to evacuate people in an emergency, in addition to having two train tubes.
One group trying to work out a compromise between cost and safety is the UN Economic Commission for Europe, which set up an expert group on tunnel safety after the 1999 Mont Blanc fire in which 39 people died. It completed an 18-month review in January this year, but it鈥檚 not clear how the review鈥檚 recommendations relate to longer, deeper tunnels. 鈥淲e were generally talking about existing tunnels,鈥� says Chris Smith, technology officer in UNECE鈥檚 transport division, adding that there鈥檚 no specific guidance for future projects. For example, standards don鈥檛 generally cover ventilation, which hasn鈥檛 been an issue in the shorter, shallower tunnels built so far.
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Rather than attempt to keep pace with ambitious future projects or demand prohibitively expensive structural features, UNECE and other European experts are shifting towards a more pragmatic view. 鈥淭here鈥檚 no such thing as zero risk,鈥� says Christopher Kaue, safety officer for AlpTransit Gotthard, the group building the 57-km Gotthard Base Tunnel. But the experts suggest that clear signs telling the public what to do in a disaster are just as critical as expensive safety technology.
When drivers entering the existing 16.3-km Gotthard road tunnel last October met a wall of smoke, most didn鈥檛 know what to do. Some got out of their cars and ran, others backed up or turned round, and others just waited in their cars for the emergency services to do something. All 11 people who died succumbed to smoke inhalation in their cars. Investigators found them more than a kilometre from the scene of the fire, where many minutes had passed between the first sight of smoke and the air becoming too thick to breathe. These people would have had plenty of time to leave their cars and walk calmly to the nearest emergency exit. But they didn鈥檛.
So the crucial principle underlying the new UNECE standards is the idea of 鈥渇air chance鈥� or 鈥渟elf-help鈥�. No matter what happens in an emergency, people should have a fair chance of saving themselves. That means clear signs inside tunnels and safe havens every few hundred metres, as well as public information campaigns aimed at tourists and commuters. Even the Swiss driving test now includes a section on what to do if you drive into a tunnel fire (see below).
The irony is that giving people a better chance of escaping can make the tunnel itself more dangerous. In the Gotthard Base Tunnel, the air needed to pressurise emergency exits and keep smoke out may also produce a wind that will fan the flames like bellows.