At 6:45 p.m., a tank wagon loaded with chlorine (a toxic gas) derailed, but did not overturn, while it was moving at a switch point of a junction between the private track of a Seveso-classified chemical plant and the public railway track. The firefighters and gendarmerie arrived on the scene. The company in charge of maintaining this section of the track (located between the plant’s fence and the first switch point on the public track) used lifting equipment to place the wagon back on the track. They finished at 6:00 a.m. The inspection authorities for classified facilities were informed. The siding that caused the wagon to derail had not been maintained: some of the sleepers were hollow, half the spikes (used to fasten the tracks to the sleepers) were missing, with the other half oxidised. This derailment drew attention to the need for the chemical plant and the freight railway operator to mutually agree on the fastening method. This document defines the parties that are in charge of operating and maintaining the junction equipment located between the terminal facilities on the siding and the national railway network (which only the railway operator is authorised to operate).