Corrugated Metal Pipe (CMP) 5
https://kilo-wiki.win/index.php/Corrugated_Steel_Plate:_Why_It_Matters_for_Durable_Culvert_Projects
Corrugated Metal Pipe (CMP) is a flexible, durable drainage solution often used in culverts, stormwater systems, and underground conduits. Its ribbed design provides strength while keeping the pipe lightweight, making it easier to handle and install than rigid alternatives. You'll spot it on roadsides or in construction sites, handling heavy loads and water flow with surprising resilience.