WIR!-Projekt: Smart Sensor for Human Factors in Railway Systems (HMI4Rail)

Abstract

This report documents the work conducted by DLR Institut für Verkehrssystemtechnik within the HMI4Rail project (FKZ 03WIR1214B, March 2023 - December 2025), which investigated physiological monitoring of train driver mental fatigue in the context of increasing automation. Building on a systematic review of the state of the art in operability detection and a structured derivation of relevant vital parameters, a standardised multimodal measurement protocol was developed encompassing HRV, EEG, EDA, eye tracking, respiration rate, and subjective sleepiness ratings. The protocol was implemented in two study environments: a simulator study (N = 14 professional train drivers, RailSET®, July–August 2024) and a real-train field study (N = 6, gesperrte Teststrecke Schwarzenberg, March 2025). Fatigue was induced via an auditory n-back task. Results across both environments consistently showed post-fatigue increases in HRV (RMSSD) and decreases in respiration rate, supporting the ecological robustness of these autonomic indicators. EEG frontal theta power did not replicate expected fatigue-related increases, highlighting the context-sensitivity of neurophysiological markers. The field study additionally revealed critical practical challenges regarding vibration-induced data loss, Bluetooth saturation, and mobile power supply. Based on the combined findings, concrete requirements for a practical real-time driver state monitoring system were derived, prioritising minimally invasive, vibration-robust wearables centred on cardiac and respiratory sensing.