open-face-wheel mole

tunnel machine

Written by

The Information Architects of Encyclopaedia Britannica

Last updated

July 1, 2026

Quick Summary

An open-face-wheel mole is a type of tunneling machine used for excavating tunnels, particularly in soft ground conditions. These machines are designed to cut through soil and weak rock using rotating cutting arms. The excavated material is then discharged onto a conveyor belt for removal.1

While effective in firm ground, the open-face-wheel mole can be susceptible to being buried in loose or running soil. This type of mole is a common variant among several designs, all of which generally operate within a protective shield. For smaller tunnels, open-face-wheel moles can be combined with pipe jacking techniques.12

Summary created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

5 Britannica Sources

Ask Britannica AI about this topic

Britannica doesn't have a full article on this topic, so we've curated a list of our relevant coverage.

tunnels and underground excavations
Soft-ground moles
The open-face-wheel type is probably the most common. In the wheel the cutter arm rotates in one direction; in a variant model it oscillates back and forth in a windshield-wiper action that is most suitable in wet, sticky ground. While suitable for firm ground, the open-face…
Read More
The open-face-wheel type is probably the most common. In the wheel the cutter arm rotates in one direction; in a variant model it oscillates back and forth in a windshield-wiper action that is most suitable in wet, sticky ground. While suitable for firm ground, the open-face…
Read More