Due to the different landform of each city, the depth of the subway will also be different. However, according to the urban subway planning, the subway depth of 0m - minus 10m is the shallow layer, and minus 10m - minus 30m is the sub shallow layer. Generally, the shallow layer and sub shallow layer are the main development. Therefore, the subway is generally 0-30m underground.
Introduction to Metro
Subway usually refers to the rapid, large volume and electric traction rail transit built in the city. The main components include tunnel, power system and vehicle. This means of transportation operates on fully closed lines, which is characterized by saving land, reducing noise, reducing interference, saving energy, reducing pollution, punctuality, fast speed, etc., while the disadvantages are high construction cost, long preliminary time, weak resistance to some disasters, etc., including earthquake, flood, fire, etc. （DeTieYiBanZaiDeXiaDuoShaoMi）