Risk Assessment of Metro Stations in the Face of Man-Made Threats and Natural Hazards (Case Study: Metro Line One Stations of Tehran Metropolis)

The urban transportation infrastructure, especially the metropolitan subway system in Tehran, which is used daily by millions of people for commuting, is recognized as one of the most vital infrastructures of the country. Any disruption in the operation of the metro network can have widespread effects on other related infrastructures, including public transportation networks and the power distribution system, as well as lead to social discontent. In this regard, in the present research, the critical assets (including human, physical, and cyber assets) of Line 1 metro stations in the Tehran metropolitan area have been assessed for risk using the RAMCAP Plus method. A wide range of human-made threats and natural hazards, as well as their quantitative consequences, have been evaluated at these stations. By calculating the quantitative values of vulnerability and the probability of events occurring, the risk value has been quantitatively determined. The results indicate that among physical and cyber assets, the signaling system, train carriages, control room, escalators, the dedicated high-voltage power distribution network, and the water guidance system at the stations are the most vulnerable assets. For human assets, passengers and staff in platform areas, station entrances, and ticket halls are the most at risk. Furthermore, the most significant threats and hazards that ranked highest in terms of frequency and risk are, in order, terrorists (both suicide and group bombings), explosive devices in the station entrances, physical and cyber sabotage, pollution, and cyber theft for the terrorist threats' category, and floods and earthquakes for the natural hazards' category.