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Simplon english summary

publié le 10 février 2011

On Saturday 6 August 2005, at 4:35 pm, underground train no. 6046 had just stopped at Simplon station, in Paris, as part of the “Porte d’Orléans - Porte de Clignancourt” trade mission being performed on line 4 of the RATP network.

As passengers were getting on and off the train, thick smoke began to rise out of carriage five. In the meantime, on the adjacent line, train 6033 stopped at the station to drop off and pick up passengers. So much smoke was billowing out of the train that the passengers of train 6046 decided to evacuate of their own accord and in accordance with the instructions of the driver of train 6033. The fire brigade was called and arrived at 4:52 pm. The RATP had trouble activating the smoke extraction system and only at 5:25 pm did the fire fighters manage to gain access to the fire, which they successfully extinguished at 6:00 pm.

Nineteen people were slightly hurt : one passenger and eighteen RATP employees who suffered from smoke inhalation. The accident could have had much more serious consequences had circumstances been slightly different (peak time, fire in a tunnel, etc.). A total of four carriages on both trains were damaged, as well as guide bars on the line, electrical cables and the “Simplon” electrical substation. Traffic on the line was able to resume the next day, but without stopping at Simplon station.

The immediate cause of the fire was a double failure of the electrical traction system of one of the motor coaches, which occurred when the train was stopped at Simplon station :
- firstly, the rupture of the servomotor contact arm that actuates the traction controller, interrupting the engine shutdown process ;
- secondly, the latent failure of the cut-off switch, which should have opened but remained in the closed position.
As a result, the motor bogie remained in “traction” mode, despite the fact that the train was stationary, causing one of the wheels to spin and its tyre to heat up with the friction before bursting and catching fire.

The second direct cause of the fire was the tyre’s high flammability and vulnerability to the risk of combustion. Indeed, tyres are made of a material that reacts very differently to the other materials affected by the fire, which behaved in a satisfactory manner. Special instructions must therefore be followed when they are used.

Various aggravating factors, of both a technical and organisational nature, delayed or hindered the fire’s subsequent management. In particular, it was not possible to run the smoke extraction system in a satisfactory manner after an initial error had been made.
The factors highlighted relate to :
- the vast number of documents to be consulted and instructions to be given by RATP’s duty inspector in order to implement the emergency procedures,
- the ineffectiveness of the smoke extraction instructions provided in the “line operator’s guide” in dealing with smoke inside Simplon station,
- the communication difficulties encountered between the various intervening parties, notably as a result of poor knowledge of the different contact numbers, the confusion that plagued the different exchanges and the often poor technical quality of the radio links.

The ten recommendations formulated after the technical enquiry cover five types of measure :
- prevention of the electrical faults that started the fire,
- prevention of the risk of the wheels spinning on all trains fitted with tyres,
- re-examination of the smoke extraction instructions provided in the line operator’s guide, to ensure that it is constantly updated, easy to use and accurate in its content,
- implementation of a centralised, remote-controlled smoke extraction system on all RATP lines where trains are fitted with tyres,
- thorough and efficient organisation of communications between the intervening parties in the event of an accident.