National Road 150 passes through the central region of Argentina and is part of a bi-oceanic corridor from Brazil to Chile. In Sierra de Valle Fertil it has traversed sedimentary rock formations where they have built five bridges and six tunnels. During construction, instabilities phenomena were seen in both tunnels and surface works. In tunnels different behaviors were observed on hard rock and soft rock. Slope instability processes include mass displacement and failures due to decompression generated by excavation. Some reported cases occured during the execution of the work, including various types of failures. In many sectors, rock masses showed a high degree of weathering. Analyses for the design and mitigation actions undertaken are described. Details emerged in the foundation of the bridges that make the section also arise.