A conceptual fatigue-motivation model to represent pedestrian movement during stair evacuation

Evacuation models often neglect the impact of fatigue on pedestrian movement during stair evacuation. While a limited number of sub-models are available in the literature to represent fatigue during evacuations, they mostly refer to simple, fixed walking speed reductions due to physical fatigue. This paper introduces a more comprehensive conceptual model for the representation of the impact of fatigue on the performance of evacuees during building stair evacuation. The model is presented considering its conceptual formulation and the issues associated with its implementation. First, a comprehensive conceptual representation of the factors concerning fatigue affecting human behaviour is discussed. The model takes into account 1) physical factors (i.e., physical fatigue), and 2) psychological factors (i.e., motivation, intended as the variable balancing the perceived risk and the perceived fatigue). Second, the application of the proposed fatigue-motivation model to a hydraulic or Newtonian based evacuation modelling tool is discussed at various levels of sophistication.