RAIB report reveals safety failures on Northern line leading to ‘trap and drag’ accidents

Credit: RAIB

The Rail Accident Investigation Branch (RAIB) has announced that it has released a report on two ‘trap and drag’ incidents at Archway and Chalk Farm stations on the Northern line earlier in 2024, revealing critical safety failures.

The first incident occurred on 18 February 2023 at 15:50 at Archway station. A passenger exiting a Northern line train had their coat trapped in the door, resulting in the passenger being dragged for about 2m before falling. The train travelled another 20m before stopping. The passenger sustained serious injuries, while their companion, who also fell, was uninjured. RAIB found that the door control system failed to detect the trapped coat, and the train operator did not realize it before departure.

The second incident happened on 20 April 2023 at 23:03 at Chalk Farm station. Another passenger’s coat became trapped as they attempted to board, and they were dragged for 20 meters before falling. Unlike the first incident, the train operator was unaware of the accident and continued the journey. The passenger sustained minor injuries and psychological distress.

Key findings from the RAIB investigation include:

• Door control system failures: The system did not detect trapped coats, allowing trains to depart
• Operator awareness: Operators were unaware of trapped coats and, in one case, dragged the passenger
• Pilot light misunderstanding: Operators misunderstood that the pilot light, indicating closed doors, could still illuminate with something trapped
• Automatic train operation influence: Operator actions may have been affected by the automatic train operation system
• Ineffective safety management: Current safety methods at the platform-train interface were insufficient to prevent these incidents.

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RAIB issued four recommendations to London Underground Limited:

• Risk understanding and mitigation: Enhance risk understanding and mitigation for trap and drag incidents
• Minimum station dwell times: Review and potentially adjust minimum station dwell times
• Design improvements: Modify task and cab environment design to improve operator awareness
• Safety documentation: Improve documentation of action plans and ensure safety briefings are recorded.

Additionally, RAIB emphasised three key learning points:

• Safety briefing documentation: Importance of documenting action plans and safety briefings
• Prompt accident reporting: Necessity of promptly reporting notifiable accidents
• Pilot light risks: Ensuring operators understand the risks of relying on the pilot light when starting the train.

These recommendations and learning points highlight the need for immediate action by London Underground Limited to enhance passenger safety and prevent future incidents.