The self rescue principle
On 12th September, I will host three 30 min roundtable discussions at the Fire Protection and Safety in Tunnels conference in Copenhagen, arranged by ARENA International Events Group. The title for the roundtable discussion is Rethinking tunnel evacuation strategies: is there a better way to improve life safety?. I guess I just would like us, me and the attendees, to take a step back and think about what we are doing, and how we are doing it. However, this have caused me to do some reading up on the current tunnel regulations in Europe and Sweden during the last couple of days, and one interesting principle that I have revisited is the self rescue principle.
Performance-based fire safety engineering requires the designer to verify that the proposed fire safety design delivers a sufficient level of safety. Underground structures, such as tunnels, are no exception. However, in underground structures, the fire rescue service is seldom considered as a part of the evacuation safety solution, simply because their role in life saving is more or less negligible in such an event. Instead, the designer needs to demonstrate that the self rescue principle is fulfilled. The principle basically means that in people in a structure must be able to rescue themselves during a fire. But what does theoretical principle mean in practical application?
For underground rail transportation systems in Sweden, the principle is deemed fulfilled if the acceptance criterions in BVH 585.30.2007 is applied. One of these relates to time and visibility, and it is stated that the self rescue principle is deemed fulfilled, as long as the evacuees do not reside in smoke for longer than approximately 15 minutes with a visibility less than 3 m (and as long as none of the other acceptance criterions related to toxicity, thermal radiation and temperature is exceeded before).
According to practitioners in the field, the acceptance criterion related to time and visibility is often the one that is exceeded first in their engineering analyses. In other words, if you are caught in a fire in an underground rail transportation system, you might want to take a deep breath before proceeding to the closest exit, which under the circumstances might not be the easiest to find. Do you think this is reasonable?