In this article, an application of cognitive work analysis (CWA), using the strategies analysis diagram (SAD) method, to model performance variability in road transport, is presented. Specifically, the method was used to describe performance variability across four road user groups (drivers, cyclists, motorcyclists and pedestrians) when turning right at an urban signalised intersection. The analysis demonstrated that the method was able to identify a comprehensive range of strategies that road users can potentially use while turning right at an intersection, thereby describing a range of performance variability within intersection systems. Furthermore, the method identified constraints, disturbances, changes in circumstances and other influences on road user performance variability. It is concluded that the CWA/SAD approach was able to describe both the different ways in which activities can be executed and disturbances, situations and constraints that create performance variability. The implications of these findings for road design and intersection safety are discussed along with the benefits and drawbacks of the methodology used.
Practitioner summary: Recently, the strategies analysis diagram was proposed as a method to support the cognitive work analysis framework in modelling performance variability. This article evaluated this method within a complex sociotechnical system, namely road transport. The application provided insight into performance variability across road user groups when turning right at intersections.