noun
inverted siphon; siphon culvert
Civil engineering term for a pipe or culvert that dips under an obstacle (e.g., a river or road) and rises again, using siphon action to convey water or sewage.
この水路は川の下を伏越しで通っている。
This waterway passes under the river via an inverted siphon.
伏越しの設計には水圧の計算が欠かせない。
Calculating water pressure is essential for designing a siphon culvert.