All passengers were rescued from the train on Wednesday after three carriages detached from the tracks injuring 11 passengers, five of them seriously, near Tiefencastel on the mountain route from Saint Moritz to Chur.
“If a section is objectively or even subjectively considered dangerous, we immediately take measures,” Christian Florin, in charge of infrastructure for the cantonal railway, told a press conference on Thursday afternoon, the ATS news agency reported.
The spectacular accident occurred shortly after midday on the heavily touristed Albula Line operated by the railway that is this year celebrating its 125th anniversary.
A crew was still working on Thursday to retrieve one of the carriages which plunged down a slope and appeared to be only prevented from rolling into a river by a stand of trees.
Passengers in another carriage dangling over the edge of the tracks walked to one end to prevent it from tipping over, according to witness reports.
Officials said the line was checked on Wednesday morning and no sign of instability on the slopes above the tracks was observed, ATS said.
Just half an hour before the derailment another train travelled in the opposite direction through the area where the landslide was to later occur without incident, the rail company said.
The driver of that train noticed nothing amiss, officials said.
The Graubünden prosecutor’s office has all the same opened an investigation to determine cause of the accident along, with the accident investigation service.
Nine of the injured passengers remained in hospital on Thursday, three of them still in serious condition, ATS said.
Most of the injured passengers on the train were Swiss, although cantonal police identified an Australian and two Japanese tourists among the victims.