The research reported in this paper is a follow-on to a five year research program conducted by General Motors in accordance with an administrative Settlement Agreement reached with the US Department of Transportation. In lieu of a vehicle recall to reduce vehicle vulnerability to post-crash fires, a research program was undertaken to provide knowledge to assist reducing the fire vulnerability for all future vehicles.
In this follow-on research project, GM agreed fund more than $4.1 million in fire related research over the period 2001-2004. This paper summarizes the projects undertaken and the preliminary results.
Research projects that have been initiated include the following: (1) statistical analysis of field data; (2) assessment of state-of-the-art in fuel safety technology; (3) test and evaluation of fuel tanks exposed to fire and impact; (4) development of recommended practices for the fire safety of 42-volt electrical systems.
For the year 2001, there were a total of 1,657 fatal crashes in which there was a fire. This is about 2.9% of all fatal crashes. Analysis of FARS data indicates that the fire rates in cars has dropped by 43.7% and LTVs (pick-ups, vans and SUVs) by 59.7% since the 1979. In 2000, the fire rate for passenger cars was 5.14 fires/million vehicle years, compared to 6.39 for light trucks.
For the years 1997-2000 the NASS/CDS contains 228 cases with fires. In these cases, frontal crashes accounted for 51.3% followed by rollover (24.1%) and side (18.4). Rear impacts accounted for the smallest fraction – 6.1%. The most frequent origin for the fire was the engine compartment, accounting for 64.5%. The fuel tank accounted for 11.4%. There were a relatively large number of unknown sources – 17.1%. The most frequent object impacted before the fire occurred was another vehicle (41.2%). However, a variety of roadside objects made up 48.7%. Narrow objects such as poles and trees contributed more than 25%.
Plastic tanks of three different shapes were evaluated to fire and impact testing as required by ECE R34, Annex 5 and US CFR 393.67 (e)(1). The ECE R34 fire test appeared to produce repeatable results and all tanks demonstrated the capability to withstand the test. All tanks passed the ECE R34 impact test. The US CFR 393.67 (e)(1) requires the tank half full of fluid to withstand a 30 ft. drop test. All new tanks passed the test. However, two of three tanks that had been in service for three years failed the test.
Research is now underway to identify state-of-the-art technologies in present day motor vehicles. Other research is oriented to developing test methods to assure the fire safety of materials used in vehicles with 42-volt electrical systems. The results of this research will be made public as it progresses.