The diversity of systemic safety drift: the role of infrastructure in the railway sector

Abstract

The paper is motivated by a concern that the “drift” metaphor may trigger stereotyped responses to accidents such as recurring requirements for better change management. The paper explores the idea that mechanisms of drift may be system-dependent by providing a qualitative analysis of the role of infrastructure in accidents and incidents in the Norwegian railway sector. An analysis of five public investigation reports on railway accidents and incidents led to the identification of four mechanisms by which infrastructure may be involved in systemic safety drift. (1) Different infrastructure generations live side by side, leading to operational complexity and less than optimal combinations of technology. (2) Operational complexity, loss of technical barriers, and increased dependence on human performance occurs when railways revert to more basic operating modes due to infrastructure breakdown or modification or maintenance work. (3) Development of infrastructure can lag behind capacity demands, causing human adaptations with implications for safety. (4) The high cost of infrastructure investments and slow funding can cause a lag in resolving safety issues and weaken the motivation for raising concerns or reporting safety incidents. A comparison between main line operations and shunting operations showed that there is considerable variety in the preconditions for drift within the railway sector. It is concluded that attention to the diversity of drift may be a starting point for tailoring safety management strategies and preventive measures to the specific challenges and opportunities of a particular sociotechnical system.