Analysis of design options and trade-offs for road tunnels incorporating suppression systems

Sammanfattning: The possibility of trade-offs in road tunnel design incorporating suppression has been evaluated. Different tunnel configurations and ventilation conditions considered to identify potential trade-offs, offering options of design alternatives for future substantial cost-benefit estimates. Suppression systems are regularly used in Australia and Japan. The interest regarding suppression systems in tunnels are growing in the rest of the world and slowly getting implemented in tunnels in Europe and other continents. There is a possibility of introducing trade-offs in tunnel design incorporating suppression. Possible trade-offs have been identified using an event tree approach as part of a qualitative risk assessment, where scenarios has been evaluated after best practice and judgment of the profession. Reliability of suppression systems is shown to be an important aspect, as well as the behavior of tunnel users. One may argue that suppression systems should always be considered as a primary option in tunnel design. As additional benefit suppression systems offer the opportunity of potential trade-offs, opening a window of opportunity for more innovative solutions and cost-benefit approaches in tunnel design. Residual value of this evaluative report and its conclusions shows that aspects like „point of no return‟, visibility and consequences of trade-offs in the event of suppression system failure must be addressed from a fire engineering and risk management point of view.