Safety
Exceeding limits of authority
Although signalling has evolved to higher levels of clarity of indications and track-side positioning, its influence on the train driver may have more of an impact than commonly thought explains Phillip Barker
A
key component of safe railway operations is the adoption of safety management and signalling systems. While
these arrangements have progressively developed in sophistication over many years, their effectiveness still relies largely on the human operator to observe procedural requirements and to respond to signal indications appropriately and exactly.
Incidents continue to occur where a train passes beyond a signal at ‘stop’. Although the majority of incidents do not result in damage or injury, for the rail operator, they do result in a loss of process, higher operating costs, and possible regulatory attention. These
incidents are also precursors to more serious incidents and accidents. Although signalling has evolved to higher levels of clarity of indications and track-side positioning, its influence on the train driver may have more of an impact than commonly thought. There can be a ‘contextual uniqueness’ in that a train driver is coerced by the situation in which a signal exists as much as the indication it displays.
The train driving task
The train driving task can be described as routine and with a lack of novelty that promotes an automatic response in which the everyday driving methodologies are used without too much conscious effort.
The issue of boredom in such a routine task as train driving is understandable and as this may contribute to lower levels of concentration, preoccupation with other tasks, however legitimate, may take preference over a response to a signal. The task of train driving is also a dynamic and decision making one, where a driver needs to plan ahead in preparation of likely events. Humans are also compulsive pattern matchers where a reaction to a situation is from a stock of stored routines. When assimilating inputs from the driving environment and the requirements of a situation, a train driver will attempt to 'explain' a signal indication based on anticipation and
February 2014 Page 87
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