A systems analysis of the Ladbroke Grove rail crash.

On 5 October 1999, near London Paddington Station, two trains collided on a main line near Ladbroke Grove. The immediate "human error" that preceded this crash was a Signal Passed At Danger (SPAD). Thirty-one people lost their lives and many more were injured. The crash prompted an extensive multi-disciplinary investigation and hearing to identify the factors that contributed to the Signal Passed At Danger event. This included the involvement of psychologists to consider the human factors "responsible" for the crash and the broader system context, including the operational and organizational environment that may have contributed. This paper summarizes the key factors identified in relation to this crash within a system analysis framework. This framework considers multiple sources of influence upon the driver in relation to the committed Signal Passed At Danger. These influences include direct factors attributable to the driver and the immediate circumstances of the event, as well as indirect, or latent, factors within the operational procedures and the management of the organization. This systemic combination of factors, not an isolated case of human error, conspired to propagate the events that resulted in the Signal Passed At Danger event and subsequent crash. This particular case demonstrates that train crashes cannot be distilled to a single causal factor. Rather, such crashes result from a system failure in which unpredicted interactions between direct and indirect influences coincide at an inopportune instant.