The slope of a culvert shall remain constant throughout the entire length of the culvert. This is generally easy to accomplish in new embankments. However, in situations where existing roadways are to be widened, it may be necessary to extend an existing culvert at a different slope. The location where the slope changes is referred to as the angle point.
If the new culvert is to be placed at a flatter grade than the existing culvert, a manhole shall be incorporated into the design at the angle point, as shown in Figure 3-10. The PEO shall contact the RHE regarding the incorporation of a manhole. The change in slope tends to create a location in the culvert that will catch debris and sediment. Providing access with a manhole will facilitate culvert maintenance.
If the new culvert is to be placed at a steeper slope than the existing culvert, the manhole can be eliminated at the angle point if debris and sedimentation have not historically been a concern at the existing culvert.
