Tunnels

---

Tunnels are long underground excavations with two or more openings to the surface, usually having a uniform cross section used for access, conveying flows, etc. Tunnels are most often used in mountainous areas. Tunnels can be divided into two basic types, lined and unlined.

Best Practices Resources

Engineering Guidelines for the Evaluation of Hydropower Projects: Chapter 12- Water Conveyance (Federal Energy Regulatory Commission)

Design Standards No. 3: Water Conveyance Facilities, Fish Facilities, and Roads and Bridges (Ch. 4: Tunnels, Shafts, and Caverns) (Bureau of Reclamation)

Citations:

Revision ID: 3396
Revision Date: 09/16/2022