RAIB issues safety reminders after Paddington derailment
The Rail Accident Investigation Branch (RAIB) issued an urgent Safety Digest on August 18, following the derailment of a Class 165 diesel multiple unit at Paddington on June 16 ( RAIL 804).
The RAIB is reminding railway operators of the importance of drivers using the resources available to them to refresh knowledge of track layouts and signals that they do not drive over regularly, as well as assessing the risk of using trap points to protect lines and why assessments should include examination of the potential consequences of derailing.
It also says drivers should be alert to the possibility that when a position light signal is cleared, the route may only be set as far as another position light signal rather than to a main signal or buffer stops, and that it is important signallers comply with any local instructions applicable to clearing position light signals when a route cannot be set all the way to a main signal or buffer stops.
The train involved was an empty stock working (3H52) that was planned to couple to a train at Platform 1 to strengthen the service. It was being held in Royal Oak sidings along with the other unit that would form the train (5H52).
The former was switched to strengthen the 1818 Paddington to Oxford rather than the 1812 to Henley-on-Thames. The signaller routed train 5H52 to signal SN6004 to clear space in the sidings for another empty stock train. The short-formed 5H52 was then routed into Platform 1 to become 1H52.
The driver of 3H52 was instructed to wait in the sidings until 1H52 had departed from Platform 1. At 1811 the route was set for 1H52 to depart. A minute later, the signaller cleared ground position light signal SN6006 for 3H52 to leave the siding. The signal authorised the train to run as far as a similar signal (SN6004), placing it in a position to run into Platform 1 as soon as 1H52 had cleared its section.
After SN6006 cleared, the driver accelerated to the linespeed of 25mph. Although he had not seen 1H52 leave Platform 1, the RAIB says “the driver had formed the impression in his mind that the clearance of signal SN6006 meant that the route was set all the way into Platform 1. Signal SN6005 was clearly visible, but the driver did not realise that it applied to his train, so he drove past it although it was showing two red lights.”
The driver applied the emergency brake as soon as he realised that his train was being diverted to the right and off the track. The first three bogies of the train ran off the end of the rails, with the front right-hand corner striking the mast of a cantilever structure supporting overhead line equipment on line 1. The cantilever dropped far enough to become a hazard for trains travelling on lines 1 and 2 into the station. The derailment caused the signal at the end of Platform 1 to turn to red and the driver of 1H52 stopped his train.
Written special instructions to signallers stipulate that when a movement starting from a position light signal requires to run via another before reaching a platform, siding or main aspect signal, the signaller must clear all the intermediate position light signals in the route first. When it is essential to route a movement to an intermediate position light signal, the signaller is required to reach a clear understanding with the driver before the movement starts.
The RAIB says that the conversation between the signaller and the driver in Royal Oak sidings should have resulted in the driver understanding that his train could not enter the station until 1H52 had departed.
Another finding from the RAIB suggests that while the driver carried copies of the line diagram in his bag and could have referred to them, he sat in the passenger accommodation and used an electronic device to access the internet. “There is no evidence that this device was used while the driver was in the driving cab of the train, or that it played any part in what happened next,” says the RAIB.