Simulation of smoke from a burning vehicle and pollution levels caused by traffic jam in a road tunnel S. Bari a, * , J. Naser b a Sustainable Energy Center, School of Advanced Manufacturing and Mechanical Engineering, University of South Australia, Mawson Lakes, SA 5095, Australia b School of Engineering and Science, Swinburne University of Technology, Australia Received 25 August 2003; accepted 1 September 2004 Available online 21 October 2004 Abstract Detailed analyses of smoke movement from a burning vehicle in a road tunnel have been carried out for the westbound Mel- bourne City Link tunnel. The time-averaged equations for velocity, pressure, temperature, and mass fraction of emissions were solved for transient condition using the CFD software FLUENT 6.0. For the analysis, a burning bus was assumed to release an equivalent energy of burning 500 l of diesel in 6 min, with vehicles upstream of the fire at a standstill. On the other hand, the vehicles downstream of the fire had enough time to escape from the tunnel through the exit portal. Due to the action of jet fans, most of the smoke was pushed downstream of the fire. The smoke had also dispersed about 55 m upstream of the fire, putting the passengers in this region at great risk. The emissions released from the vehicles in the jam, with their engines running, also posed a threat to human health. Within 8 min after the fire had started, the mass concentrations of O 2 , CO 2 and CO were in the ranges of 0.12– 0.15, 0.08–0.11 and 0.0006–0.0014, respectively. Therefore, quick evacuation of the passengers is essential in the event of a fire in the tunnel. Ó 2004 Elsevier Ltd. All rights reserved. Keywords: Tunnel; Fire; Smoke; Traffic jam; Pollution 1. Introduction Ventilation of tunnels is necessary to remove pollut- ants emitted by vehicles and to control smoke in the event of fire. In short tunnels, the airflow induced by the moving vehicles (piston effect) is usually sufficient to drive fresh air in and push polluted air out of the tun- nel (Cooley and Turkey, 1965; Goosens et al., 1994; McCormick, 1994; Rosenhead, 1963; Naser and Murad, 2002). In long tunnels, however, mechanical ventilation systems, such as jet fans and exhaust shafts, are essential in addition to the piston effect to augment the airflow in- side the tunnel to keep the levels of toxic gases within safety limits (Cooley and Turkey, 1965; McCormick, 1994; Casale et al., 1996; Ferro et al., 1991). Assessments of airflow patterns and fires in tunnels, railway plat- forms and other complex structures have been done by mathematical models using computational fluid dynam- ics (CFD) techniques (Rhodes, 1996; Rhodes et al., 1991a,b). The predicted velocities and temperatures of these studies were validated mainly by comparing them with room experiments (Kumar and Cox, 1985; Biollay and Chasse, 1996). Studies on how the heat release rates of the fires were affected by the ventilation in tunnels were done by several authors (Carvel et al., 2001; Kunsch, 2002). It was found that forced ventilation had a greater enhancing effect on the heat release rates 0886-7798/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.tust.2004.09.002 * Corresponding author. Fax: +618 8302 3380. E-mail address: saiful.bari@unisa.edu.au (S. Bari). www.elsevier.com/locate/tust Tunnelling and Underground Space Technology 20 (2005) 281–290 Tunnelling and Underground Space Technology incorporating Trenchless Technology Research