There is some uncertainty in the nature of tunnel excavation operations and this is an important part of the uncertainty due to unknown geological and geotechnical conditions. This paper proposes a risk assessment approach for problems which may arise during tunneling operations. A new model has been developed for the risk management of line 3 of the Mashhad subway (Iran’s second biggest city) applying a hybridization of game theory and fuzzy theory. Using questionnaires, appropriate responses to key risks are suggested based on modelling of game theory and categorized and ranked by importance. Linear programming problems are introduced to compute the average, optimistic, and pessimistic game values and their corresponding optimal strategies. This is the first work in this field to discuss geological and geotechnical risks in a hierarchy fashion. Hierarchy means that the ranking is done at different levels and each level has its own importance. The results indicate that providing the engineering geological profile along the route using obtained information and changing the excavation parameters based on it, is the most significant risk response. Using geophysical methods for subsurface studies and Excavating trenches for shallow investigations on the tunnel excavation route is ranked at the next level of importance.

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