Culverts are channels where roads or railways intersect with ditches, so that water can flow under the roads. They have the same function as bridges, but usually have smaller apertures and shapes, such as pipes, boxes and arches. In addition, the culvert is also a cave-type water conservancy facility with a gate to adjust the water volume.
Abutment back is an architectural vocabulary, which refers to the bridge and the bottom structure of the bridge ~ the joint between the bridge and subgrade.