Failure of a catch fence designed to retain falling debris appears to have been a major factor in a fatal rail crash in northern Italy this week.
At least nine people were killed and 30 injured when a landslide slammed into a commuter train near the town of Merano in the province of Bolzano.
It is understood the landslide was triggered either by the failure of an irrigation pipe in an orchard upslope of the railway line or by an uncharted aquifer.
The two-carriage train, filled with commuters, was passing by at the exact moment of the landslide.
“A mass of mud and water knocked down the first carriage into a ditch,” said a fire servicespokesman. “All of the dead were in the first carriage, which was pulled down into the ditch.”
The railway line runs in a deep cutting alongside the Adige River.
The embankment is supported by a masonry retaining wall approximately 4m high, with a 2.5m tall catch fence above to restrain debris.
Photographs taken after the accident clearly show that the catch fence above the retaining wall had failed.
The catch fence comprises I-section steel beams anchored into the retaining wall at around 5m centres. Each post is anchored near the top at a 45º angle into the soil. Ten horizontal steel cables then pass through the I-sections to form the fence. The cables are tensioned every 10th post.
Bolzano prosecutor Guido Rispoli has ordered a full investigation into the accident, with a three-man investigating team expected to be named on Monday. The team will comprise a geologist and two engineers.
The investigation will begin on Monday once the damaged train was removed from the tracks. This was taking place as NCE went to press on Tuesday evening.
“We must first ascertain the causes of the landslide,” he told Italian news agency Ansa. “It must be established whether the irrigation system was the sole cause of
the disaster or if there are contributing factors, such as the presence of aquifers,” he said.
The railway infrastructure was relatively new, the line having reopened in 2005 after 20 years of disuse. The retaining wall was reconditioned for the 2005 reopening and it is understood the catch fence was added at this time.
The railway reinstatement was carried out by state-owned firm Strutture Transporto Alto Adige (STA) and is owned and operated by state-owned Infrastutture Ferroviare Alto Adige (SBA). A largely privately-owned Trasporto Locale (SAD) concession operates the trains. The owner of the orchard remains unclear.
The accident happened shortly after 9am local time on Monday. The train had been nearing its destination of Merano, about 290km north of Venice, after departing from the small town of Malles.