The development and validity of an objective indicator of fatigue for frontline safety critical workers

The aim of this thesis was to develop and validate an objective indicator of fatigue for frontline safety critical workers. This thesis was carried out in partnership with Arriva Trains Wales (ATW). The rationale for developing an alternative objective indicator of fatigue stems from the fact that the current biomathematical model of fatigue used at ATW was found to be an ineffective predictor of train driver’s fatigue levels. In addition, observations from inside the cabin identified that noise, environmental temperature, incomplete train improvements, and cabin working conditions were also major issues that could contribute towards safety incidents when fatigued. As a result, clear evidence was found that an alternative objective indicator of fatigue was needed to support the fatigue risk management system (FRMS) at ATW. In a controlled laboratory setting, the 10-minute psychomotor vigilance task (10-min PVT) has become the widely accepted ‘gold standard’ tool for assessing the impact of sleep deprivation and fatigue on human cognitive neurobehavioral performance for monitoring temporal changes in attention. Therefore, several studies were carried out to replicate and validate an alternative online mobile version of the 10-min PVT i.e., online 10-min m-PVT, a shorter version i.e., online 5-min m-PVT as well as developing an offline iOS mobile app version i.e., offline 10-min m-PVT. Findings from these studies identified that the online 10-min m-PVT using the time-of-day and time-on-task paradigm was sufficiently sensitive in detecting levels of fatigue, while the online 5-min m-PVT was able to provide an objective indicator of simulated workload fatigue. The offline 10-min m-PVT was also found to be sensitive at detecting levels of fatigue for train drivers in their operational setting. Further research is now needed to investigate whether a shorter offline 5-min m-PVT could still be sensitive enough at detecting levels of fatigue for frontline safety critical workers