Shared Learning NRL21-02 - Learning from others - a serious train accident near miss

Shared Learning NRL21-02 - Learning from others - a serious train accident near miss


On 21st June 2020 at 21:43, a near miss occurred between two passenger trains at London Underground's Chalfont & Latimer station.

A southbound Chiltern Railways train travelled towards a stationary northbound Metropolitan line train on the same track, and stopped only about 23 metres away.

The Chiltern Railways train had passed a signal at danger (a SPAD) and had been automatically stopped by a tripcock train protection system.

The driver reset the tripcock and continued without seeking authority, running through a set of points and going too fast over a crossover onto the line occupied by the other train.

The driver decided to proceed without authority because he did not remember passing the red signal and believed the tripcock activation had been spurious.

His training in how to use a safety system was inadequate.

No one was hurt but the points and signalling system were damaged, causing disruption.

The Rail Accident Investigation Branch (RAIB) report contains a lot of learning which is immediately relevant to Network Rail.


The driver was probably fatigued.

He suffered sleep apnoea (stopping breathing when asleep) and type 2 diabetes, both of which disturbed his sleep.

This had not been recognised in the medical examinations.

The driver had a long history of safety events but gaps in line manager resource had contributed to ineffective action to address knowledge gaps and monitor performance.

Training and competence management were ineffective.

RAIB commented about a safety brief using over 100 PowerPoint slides.

RAIB also found gaps in shared risk management between the different companies involved.

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