Learning not blaming: Investigating ten fatal road traffic collisions using STAMP-CAST

There have been strong calls in the research literature for the adoption of system-based approaches to further reduce road casualties. However, person-based approaches remain at the forefront of both national and local-level decision-making around road safety in the UK. Focusing on person-based approaches inhibits learning across the system. Practical examples are needed to support adoption of system-based approaches and ensure safety learning is maximised within the industry. This study builds on previous work (Staton et al., 2022) mapping the control structure for the municipal area of Cambridgeshire, UK. It utilizes a system-based accident investigation method: Causal Analysis based on System Theory (CAST) (Leveson, 2019). The method is based on Rasmussen’s Risk Management Framework and is used to identify weaknesses in the control structure across the entire sociotechnical system. This supports understanding why the collision occurred and prevention of similar future events, rather than apportioning blame. In the study, CAST is used to investigate a random sample of ten fatal collisions that occurred in Cambridgeshire between 2018 and 2020. The investigations were conducted retrospectively using police forensic collision investigation files that had already concluded crown or coroner’s court proceedings. Across all ten collisions investigated, 21 different types of actor were identified across all levels of the system, each of whom played some role in at least one of the collisions. As a result, 49 specific recommendations are made concerning these actor’s roles in preventing future road deaths and serious injuries. In addition, 11 system-wide recommendations are made relating to communication and coordination; the safety information system; safety culture; design of the safety management system; changes and dynamics over time; and economic factors in the system environment. This study demonstrates that the CAST method is a viable tool for learning in the road safety industry and provides a taxonomy of system hazards, alongside the system control structure from Staton et al. (2022), to support any future analysis using this method. The use of CAST identifies the importance of controls within the road transport system and that currently, despite having one of the best road safety records in the world, the existing controls in place in the UK are insufficient to prevent serious injury and death occurring daily and are in danger of being eroded further through a political agenda of deregulation. This study reinforces that road safety requires system-based approaches and the strength of the CAST method in identifying system-wide recommendations which can be used in support of a Safe System approach to provide recommendations across the Safe System pillars.