In order to increase the knowledge on human behaviour in smoke, an evacuation experiment was performed in a road tunnel in Stockholm in July 2014. Sixty-six participants, who were instructed to individually evacuate the tunnel, took part. Participants' walking speeds were measured in a smoke-filled section, as well as in a smoke-free section, of the tunnel. The walking speeds in non-irritant ... [Show full abstract] smoke were measured for extinction coefficients in the range of 0.5–1.1 m⁻¹, which corresponds to approximately 2–4 m of visibility (for light reflecting signs). In addition, way-finding and exit choice in smoke were also investigated. Particularly, different emergency exit portal designs were evaluated in the smoke-filled section of the tunnel. The novel data-set on walking speed in smoke is presented, including coupled data on obstructed (movement in smoke) and unobstructed (smoke-free movement) walking speed. Results show that there is a weak relationship between an individual's ability to walk in smoke and the unobstructed walking speed, but more research is needed in this area. In addition, the results relating to way-finding and exit choice demonstrated that the emergency exit portal design in the experiments was appropriate for the intended use. However, in order to increase the performance of the design, the portal may be complemented with information signs on the wall opposite to the exit, namely way-finding signs including distances to the closest emergency exits on both tunnel walls, and a loudspeaker installation that can inform evacuees about the location of available exits.