The derailment at Grayrigg (NCE last week) occurred on a facing crossover used only during maintenance work and on curved track.
Traditionally Railway engineers avoided facing points because of the likelihood of derailment should the points be inadvertently changed or fail beneath a train. However, this was before signalling and point interlocking systems became widespread.
Infamously the high-speed crash of a London to Scotland express killing 13 passengers and injuring 30 at Wigan on the WCML in 1873 was reputedly caused by facing points moving beneath the train.
Facing points are a necessity and are safe if they are operated and maintained correctly. But they do pose a risk if they are faulty and it is no coincidence that the Potters Bar accident took place on facing points.
At the Cumbria derailment the train was apparently travelling at high speed on a left-hand curve. The left-hand wheel flanges, therefore, would be more likely to strike the switch blade if the gap to the left-hand stock rail had been eroded.
The risk of derailments could be further reduced if facing crossovers are restricted to straight track. Where this is impracticable then more stringent inspection or physical tests would be desirable especially where crossovers are operated infrequently and problems lie undetected.
Alan C G Hayward (F), Chepstow, acgh@email. com