Walking speed in completely darkened full-scale tunnel experiments.

• We measured the perfectly darkened walking speed using eye-mask in real tunnel. • Walking speed was approximately lognormal, gamma and normal distributed. • Two female participants gotten lost their route and suspended the walking. • We compare with the past researches and the minimum values. • Tunnel wall could be guide role and support to walk in the tunnel. When a serious tunnel fire occurs, dense smoke obscures the ceiling lights and pedestrians must evacuate the darkened tunnel with limited visibility. The precise walking speed in such situations has never been clarified, although indoor walking speeds in darkness are said to be 0.325 m/s for subjects unfamiliar with the environment and 0.705 m/s for subjects familiar with it (Togawa, 1955). The walking speed in a dark tunnel is extremely slow in evacuation situations and must be determined accurately to assess tunnel fire safety. Therefore, this study conducted full-scale tunnel experiments to measure the walking speeds of participants wearing blindfolds. The tests were conducted in the disused ex-Tonokuchi tunnel in Fukui, Japan, in 2016 and 2017. Age and gender were confirmed to have a small influence on walking speed. The results clarified that participants' walking speeds were approximately lognormally distributed within a 95% interval (using the 2.5th and 97.5th percentiles of the distribution as endpoints, which are 0.24 and 0.88 m/s with a mean value of 0.49 m/s). Two female participants became lost and gave up trying to evacuate, which generated a cancellation rate of 0.6% of the total number of evacuees. [ABSTRACT FROM AUTHOR]