A highway culvert inlet collar is disclosed having a plate member and a pipe adapter. The plate member has a front face, a rear face, a peripheral side edge intermediate the front face and the rear face, and a tapered inlet face portion adjacent the front face. The front face has a front face effective width at least twice that of the tapered inlet face portion effective width of the tapered inlet face portion. The pipe adapter has a first end and a second end, an interior surface and an exterior surface. The front face has an interior edge and an exterior edge. The tapered inlet face portion is located centrally of the front face and is preferably angled 45.degree. rearwardly from the front face. The pipe adapter is preferably oriented perpendicularly to the rear face. The tapered inlet face portion extends from the front face interior edge to a tapered face interior edge. The pipe adapter is attached to the plate member intermediate the peripheral side edge and the tapered face interior edge. The collar is also disclosed in combination with plastic pipe, preferably corrugated.