Abstarct: In this study, the identification, ranking and evaluation of factors affecting safety in tunneling with a case study of a Tehran-Shomal Freeway-Lot1 have been presented. This assessment can be considered as providing solutions to the risks and damage in tunneling, which reduces the direct and indirect costs of short-term and long-term planning. In order to achieve the objectives of this study, the previous studies were first studied and the most important parameters affecting safety in tunneling were identified. Subsequently, questionnaires were designed to understand the importance of each of the parameters affecting safety in tunneling and questionnaire experts. Cronbach's alpha coefficient was used to validate the questionnaires, which showed good reliability for the questionnaires. Then, using Fuzzy Delphi Hierarchy Process analysis (FDAHP), weights and significance of each of the parameters affecting safety in tunneling were determined. Using the results of this method, a new classification system was presented. This system, called the Tunneling Safety Index (TSi), allocates a score of 10 to 100 in total to the tunnels. Then the safety assessment in tunneling is classified into five classes: very good, good, moderate, weak and very weak. After introducing a new classification system, in order to investigate the efficiency of the method, the information of two tunnel tunnels B_2 and AB_1 from the Tehran-Shomal freeway-Lot1 consists of tunnels 6 (double arches), 1-7 left and 1-7 right of AB_1 and The 9 left, 9 right, 11 double arches, 12 left and 12 right tunnels from the B_2 were collected. The tunnels were then compared with the classification system and compared with the general condition of the tunnels, which showed good comparisons.