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Disturbing parallels with Potters Bar

News - Initial investigations into Friday's crash in Grayrigg, Cumbria, reveal striking similarities with the Potters Bar accident five years ago.

Grayrigg 2007

On Friday 23 February 2007, the 17:15 Virgin West Coast Main Line train from Euston to Glasgow passed just southwest of the Cumbrian village of Grayrigg late in the evening.

It followed a straight section of track running west-east, over a viaduct, through a cutting, and over crossing points Lambrigg 2B at 20:15. Incorrectly set points caused the train to derail at more than 90mph.

The train continued for 600m, out of the cutting and onto an embankment. The engine unit collided with overhead cable gantries, causing it to jacknife, and detach from the carriages.

The remaining eight carriages derailed, with the first coming to rest half way down the embankment, perpendicular to the track. The next four carriages overturned and slid down the embankment, their falls cushioned by trees. The remaining carriages remained upright.

Of the 115 passengers and crew, 22 required hospital treatment and one, 84-year-old Margaret Masson, later died from her injuries. As NCE went to press, five remained in hospital.

Driver Ian Black was in a serious but stable condition, while four others, including Masson's daughter Margaret Langley, are in a stable condition.

As the investigation focused on the points, Network Rail put in place a programme to check more than 900 sets of points in the days following the crash.

The Rail Accident Investigation Branch (RAIB) produced an interim report three days after the crash.

The RAIB's interim report concluded that:

l the immediate cause of the accident was the condition of the stretcher bar arrangement at points 2B at Lambrigg crossover. This resulted in the loss of gauge separation of the points switch blades

there was no evidence that the driving of train, the condition of train or the signalling control system contributed to the accident

one of three stretcher bars was missing from points 2B

bolts that secured the lock bar and another stretcher bar were not in place

some of the missing bolts and associated nuts and washers were found in the ballast

there was no evidence that the stretcher bar had been wrenched free

two of the stretcher bars were fractured, in one case most likely by the derailment but the other fracture could have predated the crash

immediately before the derailment, the left hand switch rail was free to move across close to the left hand stock rail while the right hand switch rail remained, correctly, against the right hand stock rail

all the train wheels derailed at the points with at least five sets of wheels crossing to the southbound line.

Potters Bar 2002

On Friday 10 May 2002, the 12:45 West Anglia Great Northern train from King's Cross to King's Lynn approached the station at Potters Bar at around lunchtime.

The train passed over the 2182A points just south of the station at 12:55pm. The points were set incorrectly and moved as the train passed over them causing a loss of gauge separation.

The right-hand switch rail closed against its stock rail and effectively 'squeezed' the wheel sets into derailment.

As the rear bogey of the fourth carriage passed over the points it was diverted onto an adjacent line, putting the carriage perpendicular to the direction of travel, at more than 95mph.

The force of the derailment caused the final carriage of the train to detach from the rest of the train and become airborne as it continued towards the station.

It smashed into the parapet of Darkes Lane bridge alongside the track, rolled over and then slid along the platform, coming to rest beneath the station canopy at 45° to the track.

Seven people died in the accident - six inside the train and a seventh from falling debris.

Another 70 were injured.

As the investigation focus moved toward the faulty points, track operator Railtrack checked more than 800 sets of points in the days following the crash.

The Health & Safety Executive led the investigation into the crash and published a report into its findings in May 2003.

The report concluded that:

the immediate cause of the derailment was the failure of the support system within points 2182A to retain the right-hand switch rail in the open position during the passage of the train over the points

the trailing bogie of the third coach and the leading bogie of the fourth coach derailed but continued in the forward direction, while the trailing bogie of the fourth coach took the turnout route

there were gaps in the maintenance schedule for this set of points

the lock stretcher bar of points 2182A had fractured, possibly due to fatigue l the main nut, lock nut and insulating bush were absent from the left-hand end of the front stretcher bar - similar components were found in the ballast

this stretcher bar had withdrawn from its retention bracket at the left-hand end and it was in contact with the ballast at this end

the main nut, lock nut and insulating bush were absent from the right-hand end of the rear stretcher bar. Similar components were found in the ballast

the right-hand end of this stretcher bar was located within the retention bracket although it was unrestrained.

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