BEA-TT

Carbonne english summary

publié le 22 janvier 2019

At 06:03 on 26 November 2013, a rail fractured when a train passed the 39+129 km mark on the right-hand rail of track 1 on the Toulouse to Tarbes line. This caused a train warning bell to malfunction. It began to ring continuously at the station at Carbonne.
This bell was not considered a safety installation and no traffic restriction is prescribed if it malfunctions. Six other trains travelled at normal speed without derailing and without their drivers reporting any abnormal impact on this section of the track before it was closed to commercial traffic at 08:50 due to scheduled infrastructure works.
At 09:50 the signal maintenance agent who had been trying to find the cause of the malfunction of the warning bell since 08:05 discovered a gap of about 1.30 m which, as it turned out, had been passed at 150 km/hour by inter-city train No. 14241.

This event, which could have been extremely serious but only led to limited material consequences, was due to three direct causes :

  • multiple failure of the rail linked to the presence of three fragile points on the rail within a short distance and a fault in the track geometry ;
  • lack of any prescription for safety measures in the event a warning device malfunctions ;
  • a delay in detecting the rail failure, as the track was not equipped with track circuits linked to the signalling system.

This analysis led BEA-TT to find preventive guidelines and make three recommendations in the three following areas :

  • monitoring and eliminating half switch points where the flange is machined in an obsolete manner, resulting in an angular point ;
  • detection of rail failures by track circuits not linked to safety installations ;
  • detection of rail failures by train drivers.