Chlorine leak, cut seal and a yard with no emergency information
At 02:00, a shunter finds a leaking wagon of UN 1017 CHLORINE, Class 2.3 (5.1, 8), loaded in 1-tonne cylinders, in a marshalling yard. The wagon’s seal is cut and one cylinder valve cap is missing. The train documents are in the locomotive 300 m away. The yard is 150 m from a residential street, and the wind is blowing toward the street. The shunters have no emergency information with them; the yard emergency plan covers only a “small spill”. The chlorine wagon is next to a tank-wagon of UN 1203 PETROL. The yard controller asks the shunters to “find the paperwork and stop the leak”. There is no breathing apparatus at the yard office. The nearest fire station is 12 minutes away.
1. What are the immediate priorities for the shunters and yard controller? Explain why the instruction to “stop the leak” is wrong.
Read the worked answer
The immediate priorities are to raise the alarm, move people away from the leak, approach from upwind, and keep ignition sources away from the petrol tank-wagon. Chlorine is toxic, oxidising and corrosive; a leak in a marshalling yard with the wind toward a residential street is a public-protection problem, not a maintenance task. The shunters have no breathing apparatus and no emergency information, so they must not try to stop the leak.
The instruction to “stop the leak” is wrong because it puts untrained staff into the toxic hazard without respiratory protection. The controller should call the emergency services and the railway emergency control, isolate the area, stop shunting in the vicinity, and establish a cordon. The chlorine wagon and the petrol tank-wagon should be treated as an escalating combined hazard: toxic gas plus a flammable liquid. Only trained responders with appropriate PPE should attempt leak control.
2. What emergency information is needed, where should it come from, and how should it be used?
Read the worked answer
The responders need the consignment note and the emergency information for UN 1017 CHLORINE, including the hazards, protective actions, leak-control advice, isolation distances and first-aid information. The documents are in the locomotive 300 m away, so they should be retrieved by a person who can do so safely, or the controller should obtain the information from the train operator’s control or the consignor. The wagon placards and UN number confirm the substance, but they do not replace the written emergency information.
The information should be used to brief the emergency services, set the cordon and decide evacuation or sheltering for the residential street. It should also tell the yard whether the petrol tank-wagon needs to be moved or protected. The train crew must have emergency information available during carriage; the fact that it was left in the locomotive and not with the shunters is a finding to record.
3. What incident reporting and security follow-up is required after the leak is controlled?
Read the worked answer
After the leak is controlled, the operator must report the incident internally and to the competent authority as required by the RID accident-reporting provisions. The report should identify the UN number, class, quantity, location, cause, injuries, evacuation, damage and emergency response. The DGSA should review the incident and include the findings in the report to management. The yard emergency plan must be revised because it covered only a “small spill”.
The cut seal and missing valve cap indicate possible tampering, so the security follow-up is separate and urgent. Preserve the seal and the cylinder as evidence, restrict access, notify the police or railway security, and review whether the consignment triggers high-consequence dangerous goods security requirements. Check the security plan, access control and whether the wagon was left unattended. Record who had access and when the seal was last verified.