It can be found on the website of China Railway 19th Bureau Company. According to the data, there is earthwork.
Earthwork is a kind of civil engineering, including site leveling, foundation pit (trench) and trench excavation, subgrade excavation, civil air defense engineering excavation, ground filling, subgrade filling and foundation pit backfilling. The qualifications of earthwork contracting enterprises are divided into Grade I, Grade II and Grade III.