The roadside trench drain is a drainage ditch installed at the edge of the roadbed. The earthy side ditch has a trapezoidal section, and the stone side ditch has a rectangular section. For some short embankments or mechanized construction, a triangular section is available. The longitudinal slope of the ditch is generally the same as the vertical slope of the road and must not be less than 0.5%. When the longitudinal slope of the side ditch is more than 3%, the side ditch needs to be reinforced. An intercepting ditch, also called a gutter, is used when the slope of the slope above the excavation slope of the roadbed is large, and is set at least 5 meters away from the excavation slope to intercept the surface water flowing down the hillside to ensure that the excavation slope is not affected by the water flow. Scoured. The intercepting ditch can be set up one or more roads as required to intercept the surface runoff from the slope. The key to intercepting the ditch is to drain it quickly to avoid water accumulation in the ditch. It is also necessary to prevent water seepage along the ditch and cause the slope to collapse. The intercepting ditch should have a reliable outlet. If necessary, a drainage ditch, drop or rapids can be provided to guide the water to the ravine or bridge culvert. Drainage ditches are the facilities that divert water from the gutters, intercepting ditches, borrow pits, or embankments to low-lying lands, natural river ditches, or bridges and culverts. When the terrain is steep and the longitudinal gradient of the drainage ditch exceeds 7%, it is advisable to set down water and rapids in order to reduce the flow rate, reduce the energy and prevent damage to the roadbed. When it is difficult to set culverts that cross over irrigation ditches, inverted siphons are often used.