Preparation of the project and execution of the building works of the platform of the high-speed railway corridor comprised between 306+680 and 313+680 kilometre posts as per the informative study on the North-Northwest High-Speed Railway Corridor. The works include the Martixe viaducts (962 meters in length and 100 meters of maximum height), Toxa River (344 meters in length by 55 meters of maximum height), Covas (984 meters in length by 86 meters of maximum height) and Os Besteiros (1,030 meters in length by 39.64 meters of maximum height), two underpasses and the building of the Agro tunnel, 820 meters in length.