BRITAIN’s Rail Accident Investigation Branch (RAIB) has issued an update on its ongoing investigation into the fatal head-on collision of two passenger trains close to Talerddig on the Shrewsbury - Aberystwyth Cambrian Line in Wales on October 21, revealing that the automatic sanding system fitted to one of the trains was not working.

RAIB says that at 19.26 on October 21, the 18.31 Transport for Wales (TfW) service from Shrewsbury to Aberystwyth, 1J25, operated by a two-car class 158 DMU, collided head-on with another class 158 DMU operating 1S71, the 19.09 Machynlleth - Shrewsbury TfW service, approximately 900m west of the passing loop at Talerddig, Powys.

RAIB says that an inspection of the automatic sanding system fitted to train 1J25 after the accident showed that the sanding hoses on the leading vehicle of this train, which would have been active at the time of the accident, were blocked and apparently unable to discharge sand. It also says that measurements of wheel-rail adhesion levels taken after the accident at various locations from the approach to Talerddig loop and the point of collision were low.

The investigation reveals that both trains were fitted with wheel-slide protection systems and an automatic sanding system, which discharges sand automatically via sanding hoses when wheel slide is detected during braking to increase available friction at the wheel-rail interface.

Train 1J25 had been due to stop in the loop at Talerddig to allow the eastbound service to pass. RAIB says that initial analysis of the data from the on-train data recorder (OTDR) fitted to train 1J25 shows that the driver applied service braking to slow the train as it neared the loop at Talerddig. Around 40 seconds after the first service brake application, the OTDR records an emergency brake demand being made. This emergency brake demand remained in place until the collision. OTDR data shows that wheel slide started during service braking and was constant during emergency braking.

While the train slowed as it entered the passing loop, it did not stop before passing the block marker positioned near the exit, rejoining the single-track line and continuing to travel for around 900m on the descending gradient before colliding with train 1S71.

A 66-year-old passenger was killed in the accident while four others were seriously injured and 11 required hospital treatment.

Speed

RAIB adds that there is conflicting evidence of the speed that each train was travelling at the time of the collision. Initial analysis indicates that train 1J25 was travelling at between 24km/h and 39km/h, while train 1S71 was travelling at around 10km/h in the opposite direction. RAIB is continuing to analyse evidence relating to the collision speed while the investigation will also seek to identify the events which led to the accident and will consider:

• the actions of those involved and any factors that may have influenced them

• the level of wheel-rail adhesion present from the approach to Talerddig loop to the point of collision

• the status and performance of the braking, wheel slide protection and sanding systems on train 1J25

• the behaviour of both trains during and following the collision

• Transport for Wales’ policies relating to low wheel-rail adhesion and how it managed the risk of low adhesion on the Cambrian Line

• Network Rail's policies relating to low wheel-rail adhesion and how it managed the risk of low adhesion on the Cambrian Line

• the processes used to assess and control the risk of overrun on the Cambrian Line, and

• any relevant underlying factors, including any actions taken in response to previous relevant safety recommendations.