Chamarat Da Tunnel is located between chengdu-kunming railway Hongfeng Station and Cha marat Station, with a total length of 6383.3 meters and a maximum buried depth of 600 meters. The line is herringbone, with an altitude of 3,200m, which is the highest point in chengdu-kunming railway. It is an extremely special tunnel on the Chengdu-Kunming line, which is thousands of miles long. It is one of the earliest railway tunnels with the longest span and the highest altitude in the history of China railway construction. It is called "the railway in the air" and "the throat of Cheng Kun". "Chamarat Da Tunnel" stretches for hundreds of kilometers in Fiona Fang, and the snow and ice weather lasts for more than four months every year, with the temperature below zero 120 days and the gale above category 5 150 days. At that time, the Chamarat-Dalian Railway Tunnel was built, and the harsh environment once made 352 martyrs sleep here. There is a local jingle: "The wind blows away stones, and there is not enough oxygen. It snows in June and wears a cotton-padded jacket in July", which is a true portrayal of the harsh environment in Chamarat.