The Rail Accident Investigation Branch (RAIB) has released an update following its preliminary investigation of Sunday evening’s collision at Salisbury. The update sheds new light on the cause of the collision and corrects many of the media reports published immediately after the accident.
The update states: “At around 18:45 hrs on 31 October 2021, train reporting number 1L53, the 17:20 hrs South Western Railway passenger service from London Waterloo to Honiton, collided with the side of train 1F30, the 17:08 hrs Great Western Railway passenger service from Portsmouth Harbour to Bristol Temple Meads. The collision took place at Salisbury Tunnel Junction, which is on the immediate approach to Fisherton Tunnel, near Salisbury in Wiltshire.
“This junction allows the Up and Down Dean lines which lead to and from Eastleigh to merge with the Up and Down Main lines which lead to and from Basingstoke. At the time of the accident train 1F30 was using the junction to join the Down Main line from the Down Dean line, while train 1L53 was approaching the junction on the Down Main line from the direction of Basingstoke.
“The impact of the collision caused the front two coaches of train 1L53 and the rear two coaches of train 1F30 to derail. Both trains continued some distance into Fisherton tunnel following the collision, before they came to a stop. Thirteen passengers and one member of railway staff required treatment in hospital as a result of the accident, which also caused significant damage to the trains and railway infrastructure involved.
“RAIB’s preliminary examination has found that the movement of train 1F30 across the junction was being protected from trains approaching on the Down Main line by signal SY31, which was at danger (displaying a red aspect). Train 1L53 passed this signal, while it was at danger, by around 220 metres, immediately prior to the collision occurring.
“Preliminary analysis of data downloaded from the On Train Data Recorder (OTDR) fitted to train 1L53 shows that the driver initially applied service braking to slow the train on approach to the caution signal before signal SY31. Around 12 seconds after service braking started, the driver made an emergency brake demand. As the train approached signal SY31, and with the emergency brake still being demanded by the driver, a second emergency brake demand was made by the train protection and warning system (TPWS).
“These emergency brake demands did not prevent the train from reaching the junction, where the collision occurred. OTDR analysis indicates that wheel slide was present both when the driver applied service braking and after emergency braking was demanded. This was almost certainly a result of low adhesion between the train’s wheels and the rails.”
Responding to an RAIB statement on Tuesday, which covered many of the same points, Network Rail’s Safety and Engineering Director, Martin Frobisher, said: “Sunday’s accident was incredibly frightening for everyone involved and our thoughts are with everyone injured or affected in any way.
“Initial findings suggest that low adhesion played a key part in causing the collision. It’s an issue that affects railways across the world and is something that we, and our train operator colleagues, work hard to combat – so that we can run trains safely and reliably throughout autumn, and why incidents such as the one in Salisbury at the weekend are incredibly rare.
“We will continue to work closely with investigators to understand what happened and what more we can do to help prevent this happening again.”
South Western Railway (SWR) has paid tribute to its driver, who received life-changing injuries in the collision. An SWR spokesperson said: “He is a deeply respected colleague, who has over 50 years’ experience of driving on this route and an excellent professional track record.
“All our drivers are regularly assessed to the highest standards and he has fully satisfied all requirements. “Initial findings indicate that the driver acted in an impeccable way in a valiant attempt to keep his passengers safe, staying at the controls throughout.”
Image credit: RAIB
