Kathimerini is publishing today the first information from the draft report of the National Organization for the Investigation of Air and Railway Accidents and Transport Safety (EODASAAM) regarding the tragedy in Tempe.
According to the publication, the draft notes that there is no data on the existence of a tank with a capacity of tens of tons or a hidden wagon in the freight train.
However, by the time the final version of the report is released, it is expected that the estimate of the existence of a quantity of 3,5-4 tons, most likely aromatic hydrocarbons, in the third wagon of the commercial train, which caught fire after the collision, will be documented.
The draft also claims that the explosion that followed the collision was not caused by a silicone oil leak from the transformers in the first two carriages of the commercial train. According to the same information, this assessment is reinforced by the fact that the transformers have only suffered minimal cracks.
As for the type of load that caused the explosion, the findings requested by the University of Pisa, the University of Ghent and the Swedish Institute have not definitively ruled on what it is, but all three have documented the most appropriate methodology – this is the "Computational Fluid Dynamics" (CFD) method – from which safe conclusions can be drawn, provided that the correct parameters are taken into account (humidity, wind speed, temperature, etc.).
The sequence of explosions
According to the publication, which cites information from the draft of the EODASAAM report, the first electric arc that creates a short circuit occurs six fractions of a second after the collision of the train engines.
The first phase of the fire concerns the first four vehicles of the two trains: the two engines of the commercial train and the engine of the passenger train, as well as the A1 first-class carriage.
Three fractions of a second later, the explosion begins from the ground, probably due to sparks from the brakes. The explosion expands upwards, forming a fire approximately 42 meters in diameter that burns for about 2 seconds.
A few seconds after the initial ignition, the draft report describes a second phase involving a new fire in an “unspecified volume or area” away from the initial fire, which then feeds and doubles in size. This sequence, according to the draft report, indicates that a significant amount of fuel is involved.
The third phase of the fires that broke out on the fateful night includes two separate fires that continue to burn at ground level, one near the engines of the commercial train, which probably also heats the silicone oils. A fire is created there that goes out on its own before consuming all the oil in the transformer. Another fire burns in the remains of the restaurant car with a strong flame and a total duration of 2 hours.
The fire in carriage B2 of the passenger train started from the bottom at 23.35 and burned its entire length "without any active firefighting until it began to burn with very intense flames, fueled by the fabrics of the large seats, the curtains and the interior materials", according to the draft report.
The three phases of conflicts
The finding, according to Kathimerini, includes all three phases from the moment of the first head-on collision to the moment each vehicle comes to a standstill in its final position.
The first phase mainly concerns the first four carriages of the two trains: the two of the commercial carriage where the engines were located and the first two of the passenger carriage where the engine and the first class of passengers were located. The initial impact is frontal and results in the carriages being thrown to one side and crashing into the wall of the motorway. The first class carriage was completely destroyed, with the seats scattered over the wider area of the accident. As the first four carriages of the two trains are disconnected from their trains, the remaining carriages are now moving more slowly due to the impact, but also the activation of the brakes. The findings show that the manual emergency brake is activated 1 second before the first, head-on, collision and that the mechanical brakes are automatically activated on the passenger train due to loss of air pressure from the 1st impact.
The second collision is also violent and takes place between the restaurant and the first wagon which was carrying steel plates.
The second collision of the remaining carriages, the passenger train's restaurant, which is its third carriage, and the commercial carriage carrying steel plates, is also frontal. This is the collision that causes serious damage to the restaurant carriage, which takes the form of a "final sigma." In the third phase of the collision, the carriages continue to collide with slightly less momentum, according to the findings.
Source: protothema
