Chosica station, the construction entered a mountainous area. After four years of work in extremely difficult climatic and terrain conditions, the railway was traversing the slopes of the mountains, building rock shelves, carving 63 tunnels with a total length of over 6,000 m and building a number of bridges.
After four years of arduous labor in harsh weather and rugged terrain, the Chosica station railway line began its ascent through mountainous regions.  The project involved extensive tunnel construction (over 6,000 meters) and bridge building to navigate the challenging slopes.