Box culvert with 4 cells (or barrels), US Hwy 93, Arizona, USA. Note that this culvert is designed to pass water. The walls between the cells or barrels much affect the "openness" or viewshed when looking through the structure. Should a structure be intended for multiple uses, including wildlife, then a single barrel, or a bridge with a better viewshed or openness is much preferred over a multi cell or multi barrel culvert.