The OMVG power transmission and transformation project is one of the important projects for the power interconnection of four West African countries (Guinea, Guinea-Bissau, Senegal, and Gambia). The L4 section contracted by SUMEC engineering as the general contractor is the section with the most complex terrain and the greatest construction difficulty in the entire OMVG project. The total length of the line route is 249 kilometers. The whole line is located in the uninhabited mountainous area, crossing the two largest rivers in Guinea. Nearly 60% of the area is located in the gorilla nature reserve, which makes the construction extremely difficult and the environmental protection requirements extremely high.