Which culvert design is used to obtain adequate hydraulic capacity under low embankments or for wide waterways?

• A. Arch
• B. Box Sections
• C. Multiple Barrels
• D. Circular

Answer: (C)

When vertical clearance is limited, the way to get more water through a culvert is to increase the total flow area without raising the crest height. Using several parallel culvert barrels achieves this by splitting the flow among multiple channels. Each barrel carries part of the discharge, so the combined cross-sectional area is larger than a single pipe or opening, which raises hydraulic capacity while keeping the structure low enough to fit under a low embankment. This arrangement also suits wide waterways because it creates a broad, unobstructed passage that reduces flow velocity and scour risk, and it allows easier distribution of the flow across the span. In contrast, a single arch or circular culvert may demand more height to pass the same volume, and a single large box culvert, while effective, may not be as adaptable to varying site constraints as multiple barrels placed side by side.