The Swiss investigating authorities say it is unlikely that the rolling stock of a freight train was responsible for setting off last Thursday’s devastating fire in the Simplon tunnel.
No one was injured in the blaze in the key rail tunnel linking Switzerland and Italy. It was reopened to traffic on Saturday.
Jean Gross, the deputy head of the federal office responsible for investigating rail and shipping accidents, told the Le Matin Dimanche newspaper that both engines of the freight train that caught fire were relatively new.
He said Switzerland has requested maintenance information from the German and Dutch railways who own the locomotives. He said the carriages did not have any electrical parts which could have caused the fire.
However, the investigators are looking into whether a tarpaulin covering one of the carriages may have touched against a contact wire creating sparks.
Since the freight train caught fire on the Italian side of the tunnel, the Italian authorities are officially in charge of the investigation, Gross said.
He added that it could take months before the affected tube of the tunnel is repaired.
For the time being, the Swiss Federal Railways is running one shuttle train an hour in each direction using the undamaged second tunnel.
Passengers for Milan, who would normally travel straight through, will have to change twice, adding about 20 minutes to their journey time.
A limited freight service will also be operated.
swissinfo.ch and agencies