'Sequence of events' before Walton derailment under investigation
It caused major disruption on Surrey's railways on 4 March
The rail watchdog's looking into the 'sequence of events' leading up to a train derailment in Walton-on-Thames.
The Rail Accident Investigation Branch (RAIB) have announced the terms of an investigation into the incident on Monday 4 March.
A South Western Railway service travelling towards London struck an unused piece of track near Walton-on-Thames at around 5:40am.
It was the first train to use the up fast line after engineering works, which included the removal of unused rails, were completed.
The train was travelling at 85mph at the time of the collision.
The RAIB say the train's leading set of wheels derailed, but it remained upright and came to a stop around 500m after the collision after the driver applied the emergency brake.
No one was injured, but the train and nearby rail infrastructure was damaged.
Rail services across Surrey were majorly disrupted, with the line between Woking and London blocked, and passengers urged to avoid Woking station.
The RAIB will look at the planning and management of work to recover unused rails, and the plans to ensure the railway was safe after the work was completed.
Their investigation will also look at the actions of those involved, and what might have influenced them.