Consultancy Services for Feasibility study and preparation of Detailed Project Report for design and construction of uni-directional twin tunnels on Phuentsholing-Thimphu highway of length 1.8km of project Dantak in Bhutan Consultancy Services for Feasibility study and preparation of Detailed Project Report for design and construction of uni-directional twin tunnels on Phuentsholing-Thimphu highway of length 1.8km of project Dantak in Bhutan