Fire incidents in buses are frequent and potentially catastrophic considering the confined space and sometimes difficult evacuation. In 2005, two major disasters occurred, one in Poland where 11 young people were killed after a collision with subsequent rapid fire development inside the bus, and the second in U.S. Texas, where a bus fire developed so quickly that it was impossible to evacuate the passengers and 23 people were killed.
A recent statistical survey of bus fires in Norway and Sweden revealed that 1 to 1.5 % of the buses in traffic are involved in a fire incident every year. Due to this high frequency of fires, SP, the Swedish National Testing and Research Institute started a two years research programme on bus fire safety in 2005 with the aim to decrease the number and consequences of bus fires. The investigation is commissioned by the Norwegian and Swedish Public Road Administrations.
The programme covers several areas such as a statistical survey of fires, material fire properties evaluation, a review of bus constructions and handling, tests for fire resisting divisions, development work on testing methods for engine room fire detection and extinguishment systems and simulation. A long-term goal is to amend the European vehicle directives with higher fire safety requirements for buses and coaches.
In Europe, currently only low fire safety levels for materials and components used in buses are required. Most of the materials are tested to horizontal flame spread with a Bunsen burner test (MVSS 302), curtains to a small flame test simulating a match (ISO 6940) and head linings to a dripping test (NF P 92 505); all are easily met.
The objective of the project is to show the low fire safety level in buses based on the tests used and to demonstrate the higher fire safety provided by modern fire performance tests.
A number of bus interior materials (wall panels, floorings, curtains, insulation, plastic panels and seats) have been tested in these modern bench scale fire tests to evaluate
- Ignition and heat release (Cone calorimeter to ISO 5660)
- Flame spread (to ISO 5658; Floorings to ISO 9239-1)
- Smoke production (Smoke chamber to ISO 5659)
- Toxic/irritant gas generation (Smoke chamber/FTIR)
The results obtained so far indicate that most of the materials currently used in buses do not pass the new fire performance tests and therefore present a considerable fire hazard.
This work has been presented at the Fire and Materials Conference in January 2007 in San Francisco. Another paper on motor vehicle fires in the USA (with 400 deaths per year) given there by well-known fire scientists described the same problems and urged the American automotive industry and authorities to increase fire safety in motor vehicles by using modern fire performance tests.
