rhythm
Trenching refers to digging soil in the middle of subgrade to form road grooves, and the dug soil is discarded.
Cultivate grass
Slotting is to form two shoulders with soil piles on both sides of subgrade to form a road groove. Using this method, residual soil or retained soil can be used for filling.
Half-digging and half-filling ditch
Half-excavation and half-filling is to excavate the road groove to the design depth of 1/2, and repair the excavated soil into a shoulder.