The art of train driving: Flexing the boundaries to manage risk within an inflexible system

Trains are the heaviest of land vehicles. In terms of design, railways are the most efficient and optimal way of mobilising these behemoths, but the task necessarily attracts risk. Human drivers are crucial to safe rail operations, but train driving is deceptively difficult. Although tracks guide the manoeuvrability of a train, very lengthy stopping distances mean that drivers must prepare to stop at places they cannot see. This is a safety concern, and inaccuracies and failures in this process create the risk for one of the largest safety issues in rail – the “SPAD”, or Signal Passed at Danger. A SPAD is an occurrence where a train passes a signal displaying a stop indication without the authority to do so (1). SPADs describe a situation where a train has travelled beyond its envelope of safety, and in more technical terms, entered into a critical failure mode. Based on figures available for public consumption, over 1,000 SPADs happen on Australia’s railways every year (2, 3). SPADs carry a huge financial burden associated with loss of services, missed shipping windows, timetabling disruption, follow-on impact to other traffic, incident investigation, retraining, and regulator fines. They are seen as a major threat to system safety and have corresponding effects on the network and for driver welfare.