Subway Risks Assessment in Different Construction Stages using AHP and TOPSIS

Background/Objectives: Considering the population growth the need for more services, demand for more underground space has increased. Underground structures including tunnels have been developed mostly because of the increased safety and decrease in space limitations at ground level. Methods/Statistical Analysis: This research has reached some results about prioritizing the risks according to the categorization of designing, execution, finance, HSE and cultural problems through determining the risks according to the indices of contingency and their impact using hierarchical AHP decision-making and TOPSIS algorithms along with collecting field data in the form of a questionnaire from experts and analyzing them leading to some suggestions for resolving them. Findings: In this research we find that the most critical risks of tunneling projects, are respectively landfall with risk score of 0.984, unsystematic excavation with risk score of 0.975, tolls with a risk score of 0.962, explosion with a risk score of 0/934, destruction or obstruction of tunnel and access routes with a risk score of 0.878, influence of toxic and hazardous gases with a risk score of 0.877, lack of HSE review during the implementation with a risk score of 0.861 and disregarding administrative details caused by high speed implementation with a risk score of 0.819, which should be considered by authorities in order to reduce and control the risks. Applications/Improvements: The present research focused on assessment of existing risks in metro projects and prioritizing them by gathering regional information through questionnaires form experts and analysis using multi-criteria decision-making methods consistent with the nature of risk of the project.