Has the traditional stone arch bridge been completely eliminated in modern society?

"Yixiantian" stone arch bridge is the largest railway stone arch bridge in the world today. The "length of a line" is located on the Dadu River where the Red Army's Long March passed. It is called Laochanggou, which is a big crack several kilometers long on the ancient Liangshan Mountain. The two mountains are parallel, and the light cuts like a knife and goes straight into the sky. Clouds are floating around the ditch. Looking up, the sky is only the width of a pole, and you can only see the sun for two hours every day, hence the name "watching the sky". The two ends of the "Yixiantian" bridge are connected with the tunnel, and the abyss is below. The original design is a double-hole 32-meter steel plate girder bridge, and the middle pier is an open caisson and a deep-buried foundation. However, because the trench bed is filled with big stones, the coverage is very thick, and the borehole of15m does not reach the bedrock, so the foundation construction is extremely difficult. Therefore, the design was changed, the middle pier was removed and a long-span hollow hinged stone arch bridge was adopted. "Yixiantian" stone arch bridge has a total length of 63.2 meters, a main span of 54 meters and a height of 26 meters. Construction started on April 1966, and it took only four months to complete the main project on August 28th. The project to build this bridge is very arduous and the conditions are very difficult. There are often some small wind fossils rolling down the cliffs on both sides, and bold monkeys often playfully launch "attacks" on these strangers-throwing stones from the mountains. Therefore, people here can't sleep without a helmet to prevent accidents.

Today, the Chengdu-Kunming line has been open to traffic for 10 years. Whenever the train passes by here, passengers should seize the passing moment and squeeze into the window to have a good look: the first and second tunnels are opposite, with cliffs and rocks on both sides, the Gu Teng is shaded by green trees, and the stone arch bridge stands proudly between the abyss.