Investigation of the Münchberg post-collision bus fire 2019-01-0631
In July 2017 a motor coach crashed in the rear end of a truck-trailer combination slowing down at the end of a traffic jam. The bus immediately burst into flames. The crash and fire resulted in 18 fatalities and 30 injured occupants. DEKRA was commissioned by the public prosecutor’s office to reconstruct the accident and to investigate, why the fire spread that fast.
The crash occurred due to a too late reaction of the bus driver caused by inattention or drowsiness. The attempt to avoid the collision led to a small overlap collision on the bus driver’s side. The trailer intruded the bus up to the front axle.
When the fire brigade arrived at the scene, the bus was completely on fire. None of the remaining senior occupants could be rescued any more. 30 occupants had rescued themselves; many of them were severely injured. Witnesses talked about an explosion like fire spread in the front part of the bus and smoke filling the passenger compartment within a few seconds.
The bus had an additional diesel fuel tank, retrofitted by the bus manufacturer, in front of the left front wheel. The battery compartment was located below the driver in front of the fuel tank. The collision destroyed the batteries and ruptured the fuel tank. The separation of tank, battery, and occupant compartments was also destroyed. Large amounts of diesel were sputtered inside the occupant compartment. The bus engine in the rear was still running. Thus, the generators were working. A short circuit between the generator to battery line and the frame led to an arc. The sputtered diesel in combination with the arc caused the intense starting fire.
The paper will describe the investigations and their results, the reactions of “experts” and politicians and compare the accident with a nearly similar one in France. It will give some suggestions for improvement.
Markus Egelhaaf, Dieter Wolpert, Stefan Luther