Jonzac english summary
On 13 December 2016, at approximately 08:30, the 447 and 462 level crossings at Pons and Jonzac, respectively, on the Saintes - Bordeaux line section were reported as "failing to open".
The Electrical Service Officer (SES) was called to rectify the LC 447 and detected a broken rail at 09:45. Investigations on LC 462 led to the discovery of a second broken rail at 10:45 and a third at 11:40.
These findings led to the freight train no. 72049 being stopped, which had just started to travel on this section of line. During the inspection, a large flat spot was detected on the first axle of the car no. 33 87 6772 698-1 located in second position in the train. No abnormalities were detected on the other cars of the train.
The following night, during a crossing repair project between Pons and Jonzac, three new rail breaks were detected.
On the 14th, a cabin inspection between Saintes and Saint-Mariens detected two new rail breaks between Pons and Jonzac.
Over the following days, walking inspections, train inspections and auscultations were conducted along the entire train route. In total, 13 rail breaks were noted on the train’s route. Twelve were in an area 50 km from the Saintes - Bordeaux line. An isolated case is located on the single track from Niort to Saintes.
These breaks were caused by violent impacts caused by the movement of a wagon in train no. 72049, on which two wheels of an axle each had a flat spot of about 110 mm.
These flat spots had appeared previously, probably following a wheel locking during an unladen route and were aggravated by another wheel locking initiated in a low-friction area located shortly after the station Mazières-en-Gâtine, the origin of the train. The axle then slid without turning to the first stop located in Niort. It started rotating again from this station.
Despite the noise and vibrations produced by the bearing of this defective axle, the train was not stopped by the running trains surveillance posts (STEM) located on its route.
The state of the track has contributed to the number of these breaks, as shown by their concentration in a small area, equipped mainly with rails dating from 1928 and 1929 and an uneven floor.
This analysis of the causes led BEA-TT to make three recommendations based on the following points :
- the self-contained empty-loaded systems fitted to certain wagons ;
- the motivation of agents performing STEM in terms of detecting the flat spots on the wheels ;
- the deployment of wheel defect detectors on the national rail network (RFN).
The BEA-TT is not making a recommendation in relation to the state of the infrastructure, as it is a well-known issue for the whole of the RFN and has already been the subject of recommendations in previous reports.