Travel risk SFAIRP Assessment: An analytic approach adopting bow-tie and barrier approaches

This paper examines the Human Factors of passenger interactions with platforms and carriage doors, especially when boarding and alighting. The ideal interaction is one that affords safe access to and from carriages, and... [ view full abstract ]

This paper examines the Human Factors of passenger interactions with platforms and carriage doors, especially when boarding and alighting. The ideal interaction is one that affords safe access to and from carriages, and securing passengers against unintended egress during travel, for as wide a range of people as practical. 

Practicality (or more specifically practicability) is mandated within international rail safety legislation, and regulators and operators assess control judgments using SFAIRP criteria (‘So Far As Is Reasonably Practicable’).

This paper outlines a semi-quantitative risk assessment method that has been developed specifically to address passenger interactions. The case study will outline the approach to risk scenario development, using cause-consequence bow-tie schematics based on human reliability rates and variations, and also the empirical approach to initiating incident frequencies and the measurement of control effectiveness. Measuring control effectiveness allows for more judicious decision-making, and a transparent case for ‘reasonable practicability'. The concept of a discrete safety measure (the ‘micromort’) is used to help determine relative priorities (whilst emphasising that there is no zero-risk option). In doing so, each of the five SFAIRP criteria are explicitly addressed, making regulatory communications and dialogue more transparent. 

This semi-quantitative approach has been developed in the Australian light rail environment, and is based on a quantitative approach developed by the author for State Rail NSW and the (then) Victorian Public Transport Corporation.