Culverts

A culvert is a conduit that allows water to pass under a road, railway, trail, or embankment. They range from small conduits to large bridges and are used to maintain drainage while minimizing surface disruption to the landscape.

Culverts come in several cross-sections. Pipe culverts are circular, elliptical, or other curved shapes; box culverts are rectangular boxes; arch culverts use a curved span. Some designs include open-bottom or partially open troughs to reduce flow resistance and support ecological passage.

Common materials include reinforced concrete, steel (corrugated or plate), and plastics such as HDPE or PVC. Design takes into account site hydrology, expected peak flow, headwater and tailwater levels, sediment transport, scour potential, and ice or debris loads. Fish passage may influence type and spacing.

Installation emphasizes proper bedding, alignment, and backfill to avoid settlement. End treatments and wingwalls control flow and erosion. Maintenance involves removing sediment and debris, inspecting for cracks or undermining, and ensuring inlet and outlet are clear after storms.

Environmental and safety considerations include effects on stream morphology and ecology. Properly designed culverts can improve connectivity and drainage, while poorly maintained or undersized culverts can cause flooding, blockages, and hazards to travelers.