06.01.15
Network Rail told to review its GSM-R system and training
Network Rail must review its GSM-R system and ensure signallers can directly contact all trains within, or leaving, their area of control.
The recommendation was made in a Rail Accident Investigation Branch (RAIB) report that looked into the unauthorised entry of a train onto a single line at Greenford in March last year.
The 11.36 passenger train from London Paddington to West Ruislip, operated by Chiltern Railways, passed two consecutive signals at danger near Greenford, west London.
However, it was only stopped when a signaller from the Marylebone signal box sent an emergency radio message to the driver. Although no-one was hurt in the incident, the unauthorised entry of a train onto a single line creates the potential for a serious collision, noted RAIB.
The investigation found that the signaller at Greenford wished to stop the train by sending an emergency call on the GSM-R radio system, but he did not attempt to do so because the information presented by the radio equipment in the signal box suggested to him that any message he sent would not reach the train. Instead, he contacted Marylebone signal box, which was able to send a message to the train.
GSM-R is intended to be a secure platform for voice and data communications between railway operational staff, including signallers and drivers. It was brought into full operation on the southern half of the national rail network, including the Greenford area, in 2013 after the equipment had been fitted to signal boxes and trains.
Since the incident, Network Rail has modified the configuration of the GSM-R radio system at Greenford, so that trains travelling between Greenford and Northolt Junction will appear on the train list on the terminal in Greenford signal box for the whole of the time that they are on the single line.
But RAIB has advised Network Rail to conduct a review of its implementation of GSM-R, particularly in respect of its configuration where signal boxes which have no GSM-R train describer feed adjoin signal boxes that automatically send train description data to GSM-R, and in areas of enhanced risk such as the entrances to single lines.
Additionally, Network Rail has been told to review and modify, as necessary, the training given to signallers in the use of GSM-R, so that signallers are given adequate opportunity to become familiar with the use of railway emergency calls, by practice, simulation or any other appropriate means.
Chiltern recommendations
The RAIB investigation also found that the driver of the passenger train did not react to the two signals at danger, for unknown reasons.
The RAIB thinks he may have assumed the train had been given ‘clear’ signals through Greenford, because of his interpretation of the meaning of the signal preceding those that he passed at danger, and he had not been stopped by signals at Greenford in the past.
Also, even though the Train Protection and Warning System (TPWS) was fitted to the train and to both the signals, it did not intervene to apply the brakes of the train, as it was intended to do. This was because the on-train TPWS equipment had self-isolated when the driver prepared the train for departure from Paddington. The isolation of the equipment was indicated by a flashing light in the cab, but the driver still drove the train.
Because of this, RAIB has recommended that Chiltern Railways should conduct a review of its driver management processes to confirm that the training and briefing given to drivers is “comprehensive” with regards to the equipment and systems that drivers use. Also, this review needs to make sure drivers know how to identify and respond to TPWS fault warnings.
Since the incident, Chiltern issued a briefing notice to its drivers on ‘Checking and Responding to TPWS Indications on Cab Mobilisation’, describing how the TPWS should behave when a driver is setting up the cab, highlighting the meaning of the flashing yellow light, and setting out the action to take if the flashing or steady yellow light appears.
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