Newswise — Washington D.C. – Scientists from China’s Nankai University have determined how to quantify the risks associated with major urban hazards, such as industrial explosions, and to apply the risk data to plan safe and sustainable cities. For an entire city, their analysis considers various major accidents, superimposes the effects of these accidents, draws “risk contours” for individual positions across the city, and assesses the city’s level of risk according to “as low as reasonably practical” (ALARP) guidelines. ALARP is an international standard for determining whether a risk is acceptable. Finally, they illustrate the risk assessment process and its usefulness in urban land planning by applying the system to a city in China.
Yafei Zhou and Mao Liu from the Center for Urban Public Safety Research, Nankai University, China, conducted the study, “Risk Assessment of Major Hazards and its Application in Urban Planning: A Case Study.” The National Science and Technology Support Project and the National Natural Science Foundation Project supported the work. The article is included in the March issue of the journal Risk Analysis, published by the Society for Risk Analysis.
China’s rapidly growing economy has generated sharp increases in industrial projects, which typically involve flammable, explosive, toxic or hazardous substances, and may contribute to leaks, fires, explosions, toxic proliferation, and other accidents. The impact of these accidents often extends to surrounding populations and can lead to casualties and property loss. Concerned Chinese communities seek to learn more about the planning of urban industrial projects to prevent major accidents, reduce accident impacts, ensure safe operations, and protect the surrounding environment. Risk analysis is vital to the planning process, which includes both the determination of safe locations for industrial projects and the careful use of surrounding lands.
The scientists developed a theoretical method to assess the major hazards of an entire city by using the individual risk (IR) index to quantify major hazard risks. IR is a probability defined as the likelihood of accident-induced death for an unprotected person in a fixed location. Initially, the assessor calculates the probabilities and consequences for all accident scenarios from all risk sources. Next, the assessor superimposes these “layers” of information, draws individual risk contours, and analyzes the resulting data against ALARP criteria. Practitioners of quantitative risk assessment use this refined data in urban planning by: (1) evaluating the consequences, severity, and likelihood of a series of accidents; (2) assigning an IR to each land area or zone; and (3) dividing the land according to acceptable risk standards.
The authors demonstrated the risk application for major hazards in urban planning by applying the system to Huainan City in Anhui Province. They obtained statistical data to determine the city’s major risks and provided advice and guidance on regional land use. The city’s major hazards included chemical plants, oil depots, and gas stations. The primary accidental consequences were gas leakage and vapor cloud explosions, which can cause large impacts on nearby populations and the environment. After they obtained an IR value for each hazard, the authors determined the risks for the entire city by superimposing the data. Lastly, they divided the risk areas according to the IR standard. The major hazards they identified served as the main priorities for guiding other types of land use. For example, the development of large public buildings, like schools and hospitals, was prohibited in Zone 1, and the allowable number of people in various residential and commercial buildings was restricted as well. In contrast, the development of large public buildings was permitted in less risky Zones 2 and 3, and the allowable number of people for residential/commercial buildings was fewer or unrestricted, respectively.
Implementation of safety plans for urban land use results in a more balanced relationship between land use and associated risk, which leads to both optimal use of urban land and decreased risk to public safety.
Risk Analysis: An International Journal is published by the nonprofit Society for Risk Analysis (SRA). SRA is a multidisciplinary, interdisciplinary, scholarly, international society that provides an open forum for all those who are interested in risk analysis. Risk analysis is broadly defined to include risk assessment, risk characterization, risk communication, risk management, and policy relating to risk, in the context of risks of concern to individuals, to public and private sector organizations, and to society at a local, regional, national, or global level. www.sra.org
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