Walking speed under emergency situation in smoke-filled tunnel with obstacles

[Display omitted] •Evacuation and normal walking speeds in smoke-filled tunnels with obstacles.•Analyzed effects of number and arrangement (aligned and random) of obstacles.•Investigated effects of varying smoke extinction coefficient.•Emergency evacuation speeds decreased with an increase in smoke density.•Obstacles significantly influenced average and maximum walking speed values. We experimentally investigated the evacuation walking speed distributions in a smoke-filled tunnel with obstacles such as a car in the evacuation route. Based on the extinction coefficient, the smoke levels were categorized into four: 0 (no smoke), I (0.01–0.5 m−1), II (0.5–1.0 m−1), and III (>1.0 m−1). The probability density functions of the evacuation walking speed for the different smoke levels were fitted to gamma, normal, and lognormal distributions. Based on the statistical results, the relationship between the probability density function of the evacuation walking speed and the smoke density was investigated. The influence of obstacles was significant on the average and maximum walking speed values and minor on the minimum walking speed values.