In most of the metropolitan cities, the need of metro railways is of vital importance which is increasing day by day. Hence there is need for excavation of tunnels for track laying as well as construction of underground railway stations, wherein precaution regarding the various aspects such as ventilation, air conditioning and fire safety is inevitable. The purpose of this paper is to study the aspects like ventilation, air conditioning and fire safety of tunnels for roads and metro railways in particular and to formulate provisional checklist for preliminary design purpose. The methodology adopted for the work includes analysis of various existing design criteria for the same. The checklist is divided into different major areas such as ventilation, air-conditioning and fire safety. An attempt is also made to formulate the design for discharge volume of ventilation in which tunnels under construction are considered. The work presented is one of the important aspects for the tunnel designer and contractor from execution and safety point of view. The work helps in planning the preliminary design parameters related to above aspects with the help of checklist that can be used as reference for the tunnel projects in general.
To gain access to the central area of the city, the sub-way remains the most viable alternative. So, invariably tunnels have to be constructed to meet the demand of increasing traffic load. Operating tunnels and subway systems has demonstrated that safety has to be planned and enforced as a high-priority policy in order to ensure that emergency situations can be managed properly and with minimal damage or loss. An appropriate emergency ventilation system is a main component of the emergency plan, recognizing that prevention is much better than dealing with the consequences of fire accidents. [1] Vehicle fires in road and rail tunnels are recognized to represent an immediate and extreme danger to the patrons of those systems. Unlike workers in the mining and civil construction industries, the general public are neither trained nor equipped to fight fires or to evacuate under deteriorating smoke conditions. The study of the UNECE (United Nations Economic Commission for Europe) entitled "Risk Analysis of Accidents in Tunnels" analyzed 176 cases of accidents involving trains in tunnels or underground railways. Out of these, 49% cases were involving fire. The result gives emphasis to design the aspects like ventilation and fire safety for effective mitigation of fire hazards. [3] Fire safety in rail and road tunnels is challenging because of the specific features of the tunnel environment such as restricted egress path, lack of approach at the place of fire origin, accumulation of smoke inside the tunnel, etc. Also, the underground stations of the Metro Corridor are to be built in the confined underground space. A large number of passengers occupy concourse and the platform, especially during the peak hours. The platforms and concourse have a limited access from outside and do not have natural ventilation. It is, therefore, essential to provide artificial ventilation in the station areas.
