Abstract
In case of fire in a bus, burn rate of interior component parts should be as low as possible , in order to guarantee enough time for the bus evacuation. Bus inner materials must comply with the flammability acceptance criteria established by 95/28/CE Directive.
An accident reconstruction team of INSIA worked on an in-depth research for the Traffic Authorities in 1996 about an accident with fire among a bus and a car. The fire propagation destroyed the bus completely. This accident caused 29 fatalities, mainly by the effects of fire. That study allowed to conclude that smoke propagation rate is bigger than the burn propagation rate. Smoke hides the safety systems, and causes breathing problems and faints. The 95/28/CE Directive does not consider aspects related to smoke.
Taking into account all these factors, INSIA has proceeded to broach an in-depth study of interior materials used nowadays in buses, related to its behaviour under fire conditions. The first part has included an assessment of bus inner materials according to 95/28/CE Directive (horizontal and vertical burn tests and melting test). These materials have been supplied by buses manufacturers trading in Spain.
After that, INSIA has developed an experience about smoke opacity measurement. Bus inner materials have been tested under flame and no flame conditions in NBS chamber according to NF
X 10 702 standard. Previosly, INSIA team has studied smoke standards valid for other means of transport (railways and aviation). These standards take into account smoke opacity and toxicity, and establish acceptance criteria for different parameters, to guarantee passengers safety.
The last part of this study includes a comparative analysis of the results obtained for bus interior materials. Several conclusions about possible behaviour of these materials under fire conditions are presented.