Published: December 31, 2017 | Last updated: July 5, 2023

What Does Adit Mean?

An adit is a horizontal or near-horizontal passageway to a larger underground excavation for the purposes of ventilation, water removal, or auxiliary entrance. The short tunnels are used in both mining and tunneling to access the main shaft at strategic points.

Adits are used in trenchless construction, particularly in larger projects with significant boreholes.

Trenchlesspedia Explains Adit

An additional entranceway to an underground excavation may be needed for a variety of reasons.

Uses for a Tunnel Adit

Air Circulation

Since safety is the greatest priority in any tunneling project, it goes without saying that the free flow of fresh air is critical when workers are working in a tunnel. Short horizontal tunnels driven through the ground to serve that purpose are called adits.

Rescue Access Point

An adit may also serve as another way into the tunnel. This may be required on an emergency basis to retrieve equipment or to assist or rescue tunnel workers.


Dewatering is another reason to build a horizontal adit to an existing tunnel. But the extra passage may also be part of the normal design of the operation.

The word adit comes from a Latin word signifying approach or entrance. The requirement for adits will vary with any tunneling operation.

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