Going solo: Hierarchical task analysis of the second driver in "two-up" (multi-person) freight rail operations

While many countries have dual-driver ("two-up") modes in freight rail, driver shortage creates increasing pressure to move to single-driver operations. While this change has implications for workload and safety, the roles of the primary and second drivers have not been systematically mapped. This mapping is the focus of this paper, which presents a hierarchical task analysis (HTA) from a multi-methods study (n = 40). Results indicated that transitioning from two-up to single driver operations will result in substantial changes in physical and cognitive workload for the remaining driver. These changes go much further than the simple loss of a crew-mate to double-check or verify actions and cues. This HTA can form the basis of an evidence-based safety case for the change from two-up to single-driver operations, as well as a platform for considering mechanisms to maintain safety and productivity for the now solo train driver.