Tunnels

---

Typical tunnel diagram (Image Source: FERC)

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, FERC

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

Citations:

Revision ID: 7319
Revision Date: 07/18/2023