A culvert is a structure that allows water to flow under a road, railroad, trail, or similar obstruction from one side to the other side. Typically embedded so as to be surrounded by soil, a culvert may be made from a pipe, reinforced concrete or other material. Culverts are commonly used both as cross-drains for ditch relief and to pass water under a road at natural drainage and stream crossings. A culvert may be a bridge-like structure designed to allow vehicle or pedestrian traffic to cross over the waterway while allowing adequate passage for the water. Culverts come in many sizes and shapes including round, elliptical, flat-bottomed, pear-shaped, and box-like constructions.
Drains are the common drainage components of the road which intercept the surface water running off the carriageway, shoulder and side slopes flanking the road. The process of surface drainage involves the collection and then disposing of the surface water. The water from the pavement surface is immediately removed by providing camber and cross slope to the pavement. The camber and the slope are designed according to the intensity of rainfall and type of pavement. To prevent infiltration of water, the road surface is made impervious as far as possible.
Highway construction and engineering includes planning, designing, and building of highways. History stands witness that good roads lead to prosperity for distant societies. If a road is well planned and then executed according to the plan, a highway can open the gates of growth and development.