Adaptation activity
Tokyo Metro has introduced measures against flood damage in the event of typhoons and torrential rains. In addition to elevating the entrances and exits of metro stations above the level of the sidewalk (Fig. 1), barriers (Fig. 2) and watertight doors (Fig. 1) that close the entire entrance have been installed to prevent water from flowing down from ground-level entrances into the stations. Street-level ventilation grates are fitted with sensor-activated anti-flooding devices
Additional measures are also in development based on maps of expected flooding prepared and published by the Tokyo Metropolitan Government, etc. and flooding simulation based on the final report of the "Expert Committee on Large-Scale Flooding" of the Central Disaster Management Council, which takes into account the effects of climate change. Depending on the predicted extent of inundation, existing flood mitigation devices are being upgraded to withstand pressures of 6m water depths at some locations (compared to the current 2m compliance), and at station entrances and exits, flood barriers are being raised (Fig. 2) and made completely watertight. If existing structures fail to withstand water pressure, they are rebuilt. In addition, watertight barriers (Fig. 3) have been installed at key locations to close off sections of tunnel in case of large-scale flooding. In the unlikely event of water intrusion, water can be pumped out.
