Signal Passed at Danger - Causes

Causes

As it takes a considerable distance to bring a train to a standstill, many Category A SPADs occur at low speed where the driver has applied the brakes too late. Very often this occurs when the signal at danger cannot be clearly discerned until close up. It can also be due to:

• Inattention
• Distraction
• Fatigue
• Misreading of an adjacent signal due to line curvature, or sighting on one beyond
• Misunderstanding
• Miscommunication with a Signaller or Shunter
• Signal being poorly lit or mis-showing

Almost all railways require a dim or dark signal to be treated as if it were displaying its most restrictive aspect, i.e., stop for a stop signal or caution for a distant signal. In most cases, the type of signal can be determined by a plate or coloured marking on the signal post. A somewhat related fault is when a semaphore signal's arm is stuck in the 'clear' position, e.g. by frost or snow.

In some situations, however, the driver is unaware that he has passed a signal at danger and so continues until a collision occurs, as in the Ladbroke Grove rail crash. In this instance, it is up to the safety system (where fitted) to apply the brakes, or for the signaller to alert the driver.