A tunnel evacuation experiment on movement speed and exit choice in smoke Enrico Ronchi a, * , Karl Fridolf b , Håkan Frantzich a , Daniel Nilsson a , Anders Lindgren Walter c , Henric Modig d a Department of Fire Safety Engineering, Lund University, Lund, Sweden b WSP Sverige ABjWSP Brand & Risk, Malm€ o, Sweden c MTO Safety, Stockholm, Sweden d The Swedish Transport Administration, Stockholm, Sweden ARTICLE INFO Keywords: Evacuation Experiment Human behaviour in fire Walking speed Road tunnel Smoke Emergency exit Design Exit choice ABSTRACT 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 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. 1. Introduction Human behaviour in road tunnel fires is of particular interest in the fire safety engineering community given the dramatic consequences of tunnel fires on life safety [22]. Fires may quickly become devastating due to the confined tunnel environment and the fire development may be rapid causing a quick deterioration of evacuation conditions [10,12]. In this context, the time component is critical when assessing the safety conditions of a road tunnel. Two main research areas within road tunnel evacuation are walking speed and route/exit choice. Previous research has, for example, focused on different issues concerning the impact of smoke on tunnel evacuation safety and how this can impact the time needed to safely evacuate a tunnel in case of emergency. This includes the investigation of the in- fluence of different way-finding installations on exit choice [6,11,16,24,26], group dynamics in dark environments [5] and the representation of walking speed and behaviour in smoke-filled environ- ments [2,3,25]. Way-finding installations may include different types of signage or lighting systems. Examples of such systems that have been proved to be effective include dynamic signage [15,21] or stripes of lights [6]. In this paper, the term obstructed walking speed is used to describe the walking speed of people in smoke-filled environments, i.e., with reduced visibility, while the term unobstructed walking speed is used to describe the walking speed of people in smoke-free environments. It should be noted that the term obstructed speed is by no means to be confused with the impact of physical obstacles (i.e. it refers to movement in smoke). Since the early studies conducted in the nineteen seventies in Japan, which today are summarized in a chapter of the Society of Fire Protection Engineering Handbook [30], it appeared evident that reduced visibility * Corresponding author. E-mail address: enrico.ronchi@brand.lth.se (E. Ronchi). Contents lists available at ScienceDirect Fire Safety Journal journal homepage: www.elsevier.com/locate/firesaf http://dx.doi.org/10.1016/j.firesaf.2017.06.002 Received 28 November 2016; Received in revised form 23 May 2017; Accepted 1 June 2017 Available online 16 June 2017 0379-7112/© 2017 Elsevier Ltd. All rights reserved. Fire Safety Journal 97 (2018) 126–136