Experimental study on the elderly’s walking speed considering smoke density and visual acuity in buildings

Abstract

To clarify the effect of visual acuity on walking speed of the elderly in the smoke-filled environment of the building, their walking speed was measured. 37 older people were selected to participate in the experiments, and their characteristics were counted, including visual acuity, height, age, and gender before the experiments. Walking speed in the smoke-free environment was also measured. The smoke density was divided into five stages from thin to thick, and each elderly person was measured three times at the same stages. The results showed that the walking speed of the elderly was divided into three stages according to the smoke density. The walking speed in the thin smoke environment is basically the same as that in the smoke-free environment. The walking speed reduces by 0.31 m/s as the extinction coefficient increases by 1 m−1 in intermediate smoke density. And in the thick smoke, walking speed reduced to 0.27 m/s. Visual acuity dominates walking speed in the smoke-filled environment, but other factors play a leading role in walking speed in the smoke-free environment. Besides, a calculation model is proposed which can predict the walking speed of the elderly by visual acuity and smoke density. This model can help to predict walking speed and evacuation process of the elderly in fire and provide a reliable basis for the performance-based design of buildings.