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Signals passed at danger at Greenford, 20 March 2014

RAIB is investigating an incident in which a passenger train passed two consecutive signals at danger near Greenford, Greater London, on 20 March 2014, and travelled a considerable distance before being stopped.

The train involved was the 11:36 hrs Chiltern Railways service from London Paddington to West Ruislip. No-one was hurt in the incident.

A freight train had passed the junction at Greenford shortly before the passenger train was due. Because this train was still occupying the line between Greenford and South Ruislip, the signaller at Greenford kept the signal at the junction at danger. The passenger train, travelling at about 20 mph (32 km/h), passed this signal and the next one, 142 yards (130 metres) further on, which was also at danger. It passed over the junction and onto the single-track section towards South Ruislip, which was still occupied by the freight train. The signaller at Greenford was unable to send an emergency radio message to the driver, but contacted the signaller at Marylebone signalling centre who was able to do so. The train was stopped after it had travelled about 1.75 miles (2.8 km) past Greenford.
 
(http://www.raib.gov.uk/cms_resources/Greenford.jpg)
Junction at Greenford, showing the second of the two signals which was passed at danger, which controls entry to the single line. The line on which the freight train had approached is at bottom left, and the line on which the passenger train subsequently approached is at bottom centre.

RAIB^s preliminary examination found that the train protection and warning system (TPWS) fitted to the train and the two signals concerned did not intervene to stop the train. This was because the on-train TPWS equipment had self-isolated when the driver prepared the train for departure from Paddington. Although the isolation of the equipment was indicated by a flashing light in the cab, the train was driven with the TPWS isolated.

RAIB^s investigation will seek to understand why the TPWS self-isolated, why the driver did not identify that the TPWS equipment was isolated and rectify the problem, and also why he did not respond to the signals at danger at Greenford. It will consider Chiltern Railways^ arrangements for training, briefing and assessing the competence of drivers. The investigation will also consider the operation of the signals at Greenford and the reasons why the signaller was not able to transmit a radio message to the driver after the train had passed the signals at danger.

RAIB^s investigation is independent of any investigation by the Office of Rail Regulation. RAIB will publish its findings at the conclusion of the investigation. This report will be available on the RAIB website.

RAIB has made three recommendations. One is addressed to Chiltern Railways, and covers the need for a review of the company^s driver management processes. The other two, addressed to Network Rail, cover the configuration of the GSM-R radio system as it affects the ability of signallers to directly contact trains that are within their areas of control, and the training given to signallers in the use of the GSM-R system. RAIB has also identified two learning points: one for signallers, relating to the use of delayed clearance of signals to warn train drivers of the state of the line ahead, and the other for train operating companies, relating to the upgrading of on-train TPWS equipment.

Although this was a scheduled passenger service, there were no passengers on the train on that day.

Hardly surprising.....