At 4:45 p.m. upstream of the train formation area of a marshalling yard, a tank car containing 85 tonnes of chlorine struck another stopped train with its brakes set. The chlorine car was part of a cut of 3 Dangerous Goods rail cars, the other 2 of which were empty, but had contained highly flammable and toxic liquids. The technicians heard the impact from the operating station. Two officers went to the scene and found that no derailment had occurred but noted that the chlorine car was damaged. The facility operator initiated its internal emergency plan. Rail traffic was interrupted, and the fire brigade checked for leaks. The internal emergency plan was lifted at 6:05 p.m. and traffic gradually resumed.
The event took place in a context of social movements and excessive activity in order to compensate for the lull that had occured the previous day. In order to facilitate the passage of an outgoing locomotive upstream of the train formation area, a technician had manually deactivated the primary braking system. When the 3 cars, including the chlorine tanker, entered their track, this system was still deactivated. At this point, the technician realised his error and decided to manually activate the secondary brakes, a few tens of meters from the first, at their maximum level. However, a single car preceded the cut of 3 railcars. It was stopped suddenly on the secondary brakes and then struck by the chlorine tanker at 25 km/h. Damage was observed on the bumpers and an axle of the chlorine tanker. In accordance with regulations, it was equipped with an energy absorption system. The operator concluded that, in addition to these measures, the railcar’s design also prevented damage.
The inspection authorities for classified facilities visited the site a few days after the accident. Event analysis pointed to human and organisational failures (procedures, design of the marshalling system and management tools). It highlighted the weaknesses within the marshalling operations based on semi-automated control devices. The organisation of the marshalling operations depended on the technicians’ ability to make good decisions within a very short period of time.
A collision with a chlorine tanker had already occurred at the station 6 months earlier (ARIA 49042).
