Risk assessment of mega-city infrastructures related to land subsidence using improved trapezoidal FAHP

This study presents an improved trapezoidal fuzzy analytic hierarchy process (FAHP) to assess the risk of mega-city infrastructures related to land subsidence. The trapezoidal fuzzy numbers are used to express the relative importance between assessment factors. A new questionnaire is proposed in this study to collect judgements from consulting experts. Both the original AHP and the trapezoidal FAHP with the new questionnaire are applied to assess the risk of infrastructures in relation to land subsidence in Shanghai. The risks assessed using the trapezoidal FAHP at locations with significant infrastructures are higher than those assessed using the original AHP. This indicates that the trapezoidal FAHP method with the new questionnaire can be used to effectively capture the high risks for significant industrial infrastructures related to land subsidence. Moreover, the obtained results were compared with the current land subsidence prevention zone, and it was observed that the existing land subsidence prevention zone in government management guidelines does not sufficiently consider the vulnerability of significant infrastructures.