Tunnel safety evaluation in the Nepal Himalaya: a case study of utilising analytic hierarchy process (AHP) for comprehensive risk assessment

Major development and infrastructure projects get a substantial amount of finance and cash each year in Nepal. Tunnelling constitutes one of a prosperous nation’s key infrastructures. One of the most difficult issues for project managers is to recognise and evaluate risks to project completion. Risks may be identified and evaluated using appropriate tools and techniques throughout project design, construction, and supervision. The tunnel construction activities are booming in recent years in Nepal; however, proper risk analysis is still lacking. Therefore, this study has implemented the Analytic Hierarchy Process (AHP) method to deter- mine the risk. The most important risk area is Geo-technical (26.04%) followed by natural hazards (15.44%) and safety-related risk (15.13%). This is mainly due to tunnel squeezing, rock mass collapse, water inrush, portal collapse and natural hazards such as landslide, fire and earthquake. The safety-related issues are worker’s safety as tunnelling consists of confined space, harmful gases from blasting, and hit by heavy equipment. This research will be important for the better planning and construction of different types of tunnels in Nepal.