The report provides a detailed explanation of the “fireball” phenomenon that occurred after the collision of two trains in Tempi on February 28, 2023. Dedes’ findings dismiss all conspiracy theories regarding illegal flammable materials, attributing the fireball’s formation to the ignition of transformer oils from the passenger train.

According to the report, two seconds before impact, an intense flash was observed, likely caused by the emergency braking of the passenger train. The commercial train also attempted to brake before the collision. The simultaneous braking of both trains generated sparks on the tracks.

Upon impact, the structure of the trains collapsed, rupturing the transformer oil tanks. This cooling oil, which has an ignition point above 300°C and an explosion point over 400°C, was released into the air in large quantities (7,200 kg in total) and mixed with atmospheric oxygen. Two ignition sources were identified: one near the tracks, triggered by braking sparks, and another above the trains, where an arc flash from the severed power line ignited the explosive oil-air mixture. This created the fireball, which gradually decreased in size as the burning gases were consumed.

The report also describes the Arc Flash phenomenon, a dangerous release of energy from an electrical arc, which contributed to the explosion. Temperatures during the event reached up to 20,000°C.

Fireball Formation Timeline (according to Dedes’ report):

• 23:18:28 – Head-on collision occurs.
• 23:18:29 – A spherical flash appears.
• 23:18:29-23:18:32 – The fireball expands in size.
• 23:18:32-23:18:40 – The fireball shrinks as combustible gases are depleted.
• The fire then spreads to the passenger train carriages, fueled by materials such as plastic seats, curtains, and insulation.

The report clarifies that the time discrepancies in photographic evidence are due to a 2-minute and 50-second offset in the highway surveillance camera’s clock.

This expert report provides a scientific explanation for the accident’s aftermath, disproving theories of illegal substances being involved in the fireball’s formation.