Safe Forests – The Psychophysiological Interrelationship Between Working Conditions and Stress of Harvester and Forwarder Drivers

The use of fully mechanized harvesting systems in Austria is of increasing importance, since the extraction of timber is rising, and the technological development of such machines allow them to operate in steep terrain. However, working in such challenging conditions leads to potential hazards and additional challenges. Those range from difficulties manoeuvring the machine through mountainous areas, over variable soil conditions, to the high level of physiological and psychological stress the drivers are facing. Furthermore, these factors can lead to high mental stress and strain, resulting in higher stand damage rates. The aim of the present work is to assess and analyse the working tasks of the machine to identify stressful work situations for both, harvester and forwarder drivers; to determine the psychophysiological response of these operators to environmental factors and slope gradient; and to evaluate the driver´s subjective stress and fatigue before and after a harvesting operation. Harvester and forwarder operators, with and without the use of traction aid winches, were examined during a work shift with a set of qualitative and quantitative methods. Sensor and video-based analysis of environmental and machine data, such as working tasks and slope gradient, was performed. Psychological measures (Questionnaires and Interviews) were taken, as well as time and space resolved physiological parameters, such as heart rate variability, galvanic skin response, emotion, and eye fixation duration in real time. First results suggest that the subjectively experienced stress and strain do not deviate from the norm for the most part, showing overall psychological wellbeing. Certain working tasks, e.g. driving forwards or manipulation on platform, were identified being stressful for the drivers, indicating a high mental workload. During these tasks a lower heart rate variability, a higher galvanic skin response, more negative than positive emotions, as well as a higher fixation duration were recorded.