A police officer stands next to a funicular tram on the 'Gloria' line in Lisbon, Portugal, where an accident occurred on the 3rd (local time). EPA=Yonhap News. 

The investigation into the tram funicular derailment accident in Lisbon, Portugal, which killed 16 people, including two Koreans, revealed that the cable connecting the two vehicles moving up and down the hill had snapped.

It was determined that the braking system was also ineffective as the cable supporting the weight of the tram broke.

According to foreign media reports, including the US daily New York Times (NYT), on the 6th (local time), the Portuguese Aviation and Railway Accident Investigation Committee stated in its preliminary investigation report that the connecting cable of the accident vehicle had snapped.

Funiculars consist of two trams, each capable of carrying around 40 passengers, connected by a cable that moves them up and down a steep hill alternately. While one tram goes up, the other goes down, and the two vehicles are connected by a cable that passes through an electric pulley at the top of the hill.

The cable connecting the two trams snapped in the accident vehicle, but the cable on the other vehicle was found to be undamaged.

The accident tram suddenly stopped near the top of the hill and began to slide backward. It then descended the hill at a rapid speed of 60 km/h, derailing and crashing into buildings.

Two brake systems were applied to the accident vehicle, but neither device was able to stop the tram from sliding down rapidly.

The investigation committee explained that it was difficult for the braking system alone to stop the tram without the support of the connecting cable.

The 'Gloria' line, where the fatal derailment occurred on the evening of the 3rd, is the second oldest of Lisbon's three funicular lines (opened in 1885). It runs a 275-meter section between Restauradores Square and the Miradouro de Santa Catarina.

This line is popular with tourists, including Koreans, as it leads to the Miradouro de Santa Catarina, offering panoramic views of Lisbon and various cultural heritage sites from a high vantage point.

Authorities are continuing to investigate the cause of the accident, including why the cable snapped, and plan to release an additional report within the next 45 days.

Yonhap News