Procedures for Validation and Calibration of Human Fatigue Models: The Fatigue Audit InterDyne Tool

This report presents the results of a study that illustrates a procedure for validating and calibrating a biomathematical fatigue prediction model for evaluating work schedules. The validation has two components: (1) establishing that the model is consistent with science in the area of human performance, sleep, and fatigue, and (2) determining that the model has a statistically reliable relationship with the risk of a human factors (HF) accident and lacks a relationship with the risk of other accidents. Calibration is achieved by showing a statistically increasing relationship between cumulative risk of an HF accident and fatigue level. A railroad accident database containing work intervals for individuals involved in 732 HF accidents and 1944 nonhuman factors accidents was used to apply this process to the Fatigue Audit InterDyne (FAID) tool. Validation of FAID was achieved, but an alternative method, comparing a previously validated and calibrated model, was necessary to calibrate FAID.