Evacuation in Complex Environments - Industrial Fire Journal

Fourth International Symposium on Tunnel Safety and Security, Frankfurt am Main, Germany, March 17-19, 2010
evacuate through narrow passages or down ladders, which means that there is an apparent risk of
injury. The environmental conditions may also impose other difficulties such as problems hearing an
evacuation alarm because of background noise and problem moving to a place of safety due to narrow
passages and obstacles in the path of travel. These types of factors make the environment complex
with regards to fire evacuation which can form extra hazards that have to be dealt with during
operation in the complex spaces.
Much of the preventive work safety relies on traditional procedures and not much work has been
published focusing on the special problems facing workers during evacuation from these complex
environments. Special attention has therefore been made to investigate the special conditions that may
be present for these environments.
The nature of the problems in the complex environments are similar to those in traditional assembly
type buildings, i.e. there are problems getting aware of the fire threat, the cues related to fires have to
be interpreted and a decision making process has to be initiated and finally there is a movement
distance between the location of the people and a safe place. Obviously, there are differences which
are related to the increased complexity of the environment. Some aspects that may increase the
complexity are:
- Visual access – limited visual overview, dim lighting, darkness, etc
- Sound level – noisy environments, background noise, etc
- Familiarity – unfamiliar environment, constantly changing environment, etc
- Obstacles and narrow passages – manholes, drops, etc
- Difficult passages or bottle-necks – ladders, remote locations (e.g. cranes), airlocks, etc
- Work that needs to be terminated properly due to safety reasons – welding, crane operation,
etc
- Isolated environment – long distance to a safe location, low visual access to the surroundings
etc.
In order to demonstrate some of the factors influencing the evacuation conditions present in the
complex environments an evacuation experiment was performed in a tunnel boring machine (TBM)
used for constructing a railway tunnel in Sweden. The TBM, which is over 240 m long and has a
diameter of over 10 metres, has currently proceeded approximately 5 kilometres into the mountain.
The typical problems for this scenario are that there is only one escape route, the noise level is high
and it is difficult to have visual access of the environment.
The safety for the tunnel workers has also been investigated using a simple one-dimensional
evacuation model. The model determines the possibility for continuous evacuation for persons in a
tunnel given a prescribed fire development. It is necessary for the tunnel construction operator to
investigate different fire scenarios that can occur as performing experiments and drills can only
capture some aspects of the possible outcome of an accident. Therefore modelling and physical
experiments have to complement each other to broader the picture and provide input for additional
safety assessment. The paper, therefore, introduces a simple MATLAB model that can be used for an
initial sensitivity analysis of the evacuation situation for the tunnel workers.
The evacuation research is part of the ongoing research project “Fire safety in tunnels during
construction” which is supported by The Swedish Civil Contingencies Agency (MSB) and led by the
Technical Research Institute of Sweden in Borås. The purpose for the main research project is to
investigate the fire behaviour, the occupant evacuation conditions and the needs for a proper rescue
operation in tunnels, which are under construction. The research project is running to the end of 2010.
This paper is based on a paper [5] presented at the 4 th International Symposium on Human Behaviour
in Fire, 13-15 July 2009.
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