NIKKEN SEKKEI URBANISM

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evacuation destinations. In some cases fundamental upgrades might be required, such as redevelopment of especially dangerous districts or buildings to secure evacuation plazas and build broad and easily understood streets.Nikken Sekkei has designed many large, integrated facilities in the city center. For the past several years, hawse have been conducting research into disaster preparedness within the city centers where those facilities are located. Based on this experience, we hope to contribute to the development of city centers that will be resilient against disasters.PREVENTING FLOODING OF URBAN UNDERGROUND SPACES Underground networksBeneath the core districts of Japan’s largest cities are many underground networks that have developed to connect underground subway stations, shopping malls, and plazas. To newcomers they are veritable urban mazes, and they are expanding every year, especially in the capital city of Tokyo where redevelopment is steadily increasing the amount of underground space. The Nikken Group has participated in many such plans, including subway stations and integrated station/urban development projects. The space beneath urban transit terminals increases public accessibility by offering shelter from the weather and car trafc, and enables convenient concentration of many kinds of urban functions.Vulnerability of underground spaces to waterIn recent years, cities throughout Japan and East and South Asia have been assaulted by ooding from tsunamis, swollen rivers, and storm surges. Flooding from rain is also occurring annually, as the heat island effect in city centers touches off torrential showers bringing more than 50mm of rain per hour. When torrential downpours occur, large volumes of rainwater can flow into the low-lying entrances to the labyrinthine network of underground urban spaces, potentially putting these spaces out of service and resulting in massive damage and threat to life. Underground spaces appear to be safe against earthquakes, but they are very vulnerable to flooding. Compared to surface streets, they are enclosed spaces with their own disaster vulnerabilities, such as a limited number of evacuation routes, difficulty in obtaining information and deciding when to begin evacuation, limited evacuation time and a high probability that lighting and other physical functions will be disabled by ooding.Countermeasures against flooding of underground spacesTo prevent damage by flooding, the Nikken Group builds on published flooding hazard maps from the initial planning stages. Flooding countermeasures are provided in the design phase, while consulting with the client, in the form of water stop plates and watertight doors at entrances to underground spaces, flooding prevention devices at subway ventilation openings, and flood gates in subway interiors. With each project, the range of solutions is being extended and improved.In underground spaces used by the public, it is especially important to provide accurate information quickly and for managers to be able to quickly stop the inow of water at entrances. Flooding prevention infrastructure and training in its use must be provided.Both in Japan and overseas, underground spaces play an important role in furthering the dense, efcient, and vibrant utilization of space. At the same time, such spaces must be safe. The Nikken Group is working to ensure that they are.EARTHQUAKE DISASTER RECOVERYThe NIGECHIZU team is a recognized volunteer club activity within the company. “NIGECHIZU” is a map visualizing risk and building consensus on the regional planning level. It uses different colors to graphically illustrate the amount of time it would take for citizens of a particular town our area to evacuate to safer, higher ground. NIGECHIZU may serve as the foundation for development within communities, and is intended to be especially useful to SUBWAY STATION FLOOD SIMULATIONSUBWAY STATION FLOOD SIMULATIONEVACUATION GUIDANCE AFFORDED TO PASSENGER NO EVACUATION GUIDANCE106 _ 107NIKKEN SEKKEI URBANISMCOLUMN

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