RAIB Investigation: Electrical arcing and fire, Tyne & Wear Metro 11/08/2014

[whole diary]

[JayMac]

From the Rail Accident Investigation Branch:

Electrical arcing and fire on a Metro train and parting of the overhead line at Walkergate station, Newcastle upon Tyne, on 11 August 2014

RAIB^▸ (Rail Accident Investigation Branch) is investigating an accident which occurred on the Tyne and Wear Metro system at Walkergate station on Monday 11 August 2014.

At 18:56 hrs a two-car Metro train, travelling from South Shields to St James, arrived at Walkergate station. While standing in the station an electrical fault occurred to a line breaker mounted on the underside of the train, which produced some smoke. It also caused the circuit breakers at the sub-stations supplying the train with electricity, via the overhead line, to trip (open). About one minute later power was restored to the train. There followed a brief fire in the area of the initial electrical fault and further smoke. Shortly afterwards, the overhead line above the train parted and the flailing ends of the wire fell on the train roof and one then fell on to the platform, producing significant arcing and sparks for around 14 seconds. Fortunately, there was no-one on the platform at the time. However, there were at least 30 passengers on the train who self-evacuated on to the platform using the train doors' emergency release handles. The fire service attended but the fire was no longer burning. No-one was reported to be injured in the accident and there was no significant damage to the interior of the train.

Image courtesy of Tyne and Wear Metro

RAIB's investigation will consider the sequence of events and factors that led to the accident, and identify any safety lessons. In particular, it will examine:

• the reasons for the electrical fault;
• the response of the staff involved, including the driver and controllers;
• the adequacy of the electrical protection arrangements; and
• actions taken since a previous accident of a similar type that occurred at South Gosforth in January 2013 (RAIB report 18/2013).

RAIB's investigation is independent of any investigations by the safety authority. RAIB will publish its findings at the conclusion of the investigation. The report will be available on the RAIB's website.

Edit note: Subsequent forum software formatting glitches corrected. CfN.

[Electric train]

1500 V dc nasty stuff

[Chris from Nailsea]

The Rail Accident Investigation Branch have released their report, available on the RAIB^▸ (Rail Accident Investigation Branch) website:

Incident in which the live overhead wire parted at Walkergate station, Tyne and Wear Metro, 11 August 2014.
 
At around 18:56 hrs on Monday 11 August 2014, a Tyne and Wear Metro train at Walkergate station, developed an electrical fault in equipment under the rear car, which tripped the power supply to the overhead wire. About a minute later, the power was remotely restored by a power controller and a fire started in the faulty equipment. The fault drew a high current from the overhead wire through the car^s pantograph, causing localised overheating and, after about 18 seconds, the wire parted. The loose ends of the live wire flailed around the train roof, showering sparks, and one end fell on the platform. A second power controller happened to observe events on station CCTV^▸ (Closed Circuit Tele Vision) and power to the overhead line was disconnected. The parted overhead wire had remained live for approximately 14 seconds.

At the time of the accident, the train doors were closed for departure and there were no passengers on the platform. About 30 passengers got out of the train after the power was turned off. There were no reported injuries, although passengers were evidently distressed.

A sustained high current was drawn because the electrical fault occurred in a part of the train^s power circuit which was not protected by on-train equipment and which could only be detected by the overhead power supply protection equipment. However, because of the way that the power was switched back on, the level of current drawn by the fault was not sufficient to immediately activate that protection. The underlying cause of the accident was the ineffective management of risks created at the interface between system components, comprising the power supply, power control and the train.

The RAIB observed that the arrangements between the infrastructure operator, Nexus, and the train operator, DB^» (Deutsche Bahn - German State Railway - about) Regio Tyne and Wear, did not effectively facilitate the sharing of relevant health and safety information on risks created within the system. It also observed deficiencies in the competence management of the power control function and in the regime for assuring the continued integrity of some electrical protection equipment.

The RAIB has made three recommendations. The first, addressed to Nexus, seeks improvements in its safety management system to provide a more effective framework for the management of its shared risks. The second, addressed to both Nexus and DB Regio Tyne and Wear, relates to the identification and evaluation of risks created at the interfaces between their organisations. The third recommendation, addressed to both organisations, seeks to achieve more comprehensive power control procedures to facilitate safe decision-making.