The high temperatures give rise to high radiation, which is important for the fire spread to other vehicles in the tunnel. Another important issue regarding the radiation is how close to the fire the fire fighters can reach before they are stopped by the high radiation. Tests performed with fire fighters in protection clothing indicate that there is a limit approximately 5 kW/m2 exposure above which the fire fighters will have difficulty to work and also feel pain after about 5 minutes.
The measurements during the large-scale fire tests, presented in the above figure show that this limit is exceeded in all of the tests, at a distance of 10 m from the set-up. The fire fighters not only need to be able to withstand the radiation, they must also be able to work in the heat.