Abstract
Aim: This study examines the results of studies of selected worldwide legal acts stipulating the distances between escape routes in road tunnels, as well as the results of the verification of selected legal restrictions resulting from numerical model simulations of hypothesised fire scenarios.
Introduction: The issues of the distances between escape routes’ significantly affecting the timing of self-rescue activities during fires in road tunnels, and related safety matters during evacuation activities, are described in the present study. These distances are controlled in Poland by the Regulation of the Ministry of Transport, Construction and Maritime Economy of 30 May 2000 on the technical conditions of road engineering objects and their locations (Journal of Laws No. 63, item 735, as amended). According to the Regulation in question, the distance between escape routes should not exceed 500 m, which, in the light of worldwide legislative acts, is one of the least rigorous requirements. The distance between escape routes depends on numerous factors and the most important are: type of vehicles passing the tunnel, traffic congestion, ventilation, heat release rate, fire-detection system and geometrical parameters. The differences between the legal acts are the basis of the described research topic.
Methodology: Analyses of selected worldwide legal acts and numerical modelling in order to check the safety conditions during evacuation were carried out for the adopted escape route variants. The time of the critical state reach in tunnels was determined and it was checked whether people were still present in tunnel after this time. Two types of tools were used: the Fire Dynamic Simulator program for assessing the time of reaching the critical environmental state, and the Pathfinder program for evacuation time calculation.
Conclusions: The results of the completed analyses proved that assuring safety during self-rescue activities road tunnels ≥ 1500 long without escape roads or with escape routes distanced every 500 m was not possible. For the considered fire scenario in question and assuming a detection time and alarm equal to 120 s, 250 m between escape routes is sufficient to guarantee safe evacuation from tunnels on fire. Furthermore, the calculation of the distance between escape routes for a given tunnel should be preceded by a risk analysis during the design stage.
Keywords: evacuation, escape routes, fire safety, road tunnels
Type of article: review article