Design criteria of subway emergency ventilation systems and the design procedure in a case study

This paper aims at recognition of proper design criteria for emergency ventilation systems in subway tunnels and designing an efficient system that can meet the selected criteria. Since the main concern of emergency ventilation design in subways is to provide the patrons with a safe and smoke-free route, the main discussion of this article deals with the requirements of the smoke management in a fire case. The approach adopted here focuses on a constructional constraint that have major interfaces with ventilation system. This specific constraint that is a main conflict between civil works of subway projects and the ventilation system is usage of mid-tunnel ventilation shafts (intershafts). This paper reviews 3 options available regarding the usage of ventilation shafts and recommends the one that is more consistent with the civil works. By choosing a case study, It is shown that a proper design makes it possible to remove the mid-tunnel shafts (intershafts) and give the duty to the station-end shafts to remove smoke in emergency cases. This options can obviate a lot of civil work concerns such as land acquisition in urban areas. It also can decrease electrical requirements (such as cabling and control system) that are obligatory if the mid-tunnel ventilation exists . The results presented here are obtained by two certified software in this field: FDS (Fire Dynamics Simulation) and SES (Subway Environmental Simulation.)