The work consisted of study and definition of the optimum solution for improving the road route in a length of 100 km, and defining necessary surface reinforcement on another 100 km of roads. In areas with a route variation, the necessary overpasses and drainage culverts were designed, with three singular bridges. The first of these, over the River Guatizalema, has been resolved with a single-span fish-beam metal latticework 67 metres wide. The second, located over the reservoir of Ardisa, dates from the 1920s and is one of the few remaining examples of reinforced concrete lattice work. An extension to the bridge was designed using metal cross braces resting on an external metal structure, maintaining the main body of the bridge. Finally, in the bridge over the La Peña reservoir, with three spans of 50-62.5-50 m, the design was for removal of the existing deck using inverse launching (the existing bridge had been launched into place in 1909) and replacement with another modern metal bridge with the required width, also launch-pushed using the same auxiliary installations.