Merișor derailment

The accident location at Merișor is situated on the line between Filiași to Simeria, commonly known as the "Jiu Valley Line", since it crosses the Charpatian Mountains along with the Jiu river, being considered one of the most scenic railway lines in Romania. The exact section at Merișor is situated on the Petroşani to Subcetate segment of the line, known for its steep inclines and twisty sections as its leaving the Petroşani basin trying to cross a hilly area to get to the Hațeg basin. When the line was electrified on 31 October 1973, a neutral section was installed a few hundred meters from the accident location, which soon became known as "the hardest neutral section in Romania" due to the fact that its situated on a steep gradient and that trains cannot go at speeds higher than 30 km/h in the area, due to the poor maintenance of the railway line. The line at the site of the accident was designed to take speeds of 60 km/h at most.

The train was made out of a CFR Class 40 locomotive, commonly classed as the LE 5100 series made by Electroputere Craiova, and 16 E-type carriages, normally used for carrying gravel, waste iron, logs, etc. The exact locomotive in question was 40-0759-7, it was made at the Electroputere works in 1983, and previously it had serviced in Bulgaria around 2008–2009, being used by "Unitranskom" at Burgas. At the time of the accident it was refurbished, but it is believed that the compressor failed. Another theory is that the INDA-type throttle installation was jammed in a superior position that would have reduced the efficiency of the braking and failed to reduce the traction motor current intensity. 40-0759-7 was also involved in another incident relating to overspeeding on inclines near Predeal before the accident.

The railway company who owned this locomotive, Unicom Tranzit was apparently involved in multiple train accidents/incidents during the time period before and after this accident, and many safety irregularities have came out after the accident. However the operating licence of this company was not suspended.