A signal passed at danger (SPAD) resulted in a Chiltern Railways passenger train stopping just 23 metres from a stationary London Underground train that was on the same line, preparing to start off in the opposite direction.
The Rail Accident Investigation Branch (RAIB) has launched an investigation to this serious near miss at Chalfont & Latimer station, Buckinghamshire, that could have been a head-on collision.
The incident took place at around 21:45 on 21 June 2020. The Chiltern Railways passenger train was travelling southbound on the Metropolitan line of the London Underground network when it passed a signal at danger (red) without authority.
The signal was protecting a junction through which a route was already set for a northbound train, waiting in Chalfont & Latimer station, to cross in front of the southbound train. Passing the signal at red resulted in an automatic brake application which stopped the southbound train around 310 metres beyond the signal.
Shortly afterwards, the train driver reset the automatic brake equipment and the train continued towards Chalfont & Latimer station, around 620 metres away.
However, as a result of the position of the points at the junction, its route towards the station took it onto the northbound line.
A northbound London Underground train was already on this line but stationary, because the signal in front of it had changed to red as a result of the southbound train passing the red signal. The two trains stopped about 23 metres apart.
There were no reports of any injuries, but some track components were damaged as the southbound train had proceeded through a route that was not set for it.
The RAIB’s investigation will identify the exact sequence of events which led to the signal being passed at danger and the subsequent near miss. It will also consider:
- The actions of the people involved;
- Chiltern Railways’ arrangements regarding the training, competence and fitness of its train drivers;
- Chiltern Railways’ management of risk associated with its drivers operating on the London Underground network;
- How risk associated with signals passed at danger by non-London Underground trains is managed on the London Underground network;
- Any relevant underlying factors.
The RAIB’s investigation will be independent of any other investigation by the railway industry or by the industry’s regulator, the Office of Rail and Road. Its findings, including any recommendations to improve safety, will be published at the conclusion of the investigation, a process which typically takes around 10 months.