A ventilation tunnel is an underground passage constructed primarily to move air rather than to carry vehicles, ore, or passengers. It is used as part of a ventilation system to supply fresh air or remove contaminated air from mines, road and rail tunnels, or other underground facilities. In mining, a ventilation tunnel may be called a ventilation drift, adit, or airway, depending on its orientation and connection to surface.
In an underground mine, a ventilation tunnel is usually designated as either an intake airway or a return airway. As an intake, it carries fresh air from a shaft, decline, or surface opening into the deeper workings. As a return, it collects air that has passed through production areas, headings, and infrastructure zones and directs it back towards exhaust openings and main mine ventilation fans. Its location and cross-section are chosen so that it can carry the required airflow with acceptable pressure loss.
From a design point of view, a ventilation tunnel must provide low resistance and safe access for inspection and maintenance. Engineers select dimensions that match the expected airflow volume and velocity limits, using smooth linings and gentle curves to reduce friction and turbulence. Rock support, drainage, and ground control are designed for long-term stability, since ventilation tunnels are often among the earliest excavations driven and are used throughout the life of the mine.
In large infrastructure projects such as road or rail tunnels, the term ventilation tunnel can also refer to parallel or cross passages dedicated to ventilation. These passages connect the main traffic tunnel to ventilation shafts or to separate service tunnels that house ducting and ventilation equipment. Air may be supplied through one tunnel and exhausted through another, forming part of a transverse or semi-transverse tunnel ventilation system.
Ventilation tunnels are closely integrated with ventilation control devices and fans. Stoppings, regulators, and doors installed inside or at the ends of these tunnels control how much air they carry and in which direction it flows. Axial or centrifugal fans may be connected directly to a ventilation tunnel to create an intake, exhaust, or recirculation route as defined by the ventilation plan.
Because they influence the overall airflow network, ventilation tunnels are carefully documented in ventilation models and plans. Changes to their length, cross-section, or connection points can significantly affect pressure and flow distribution, so any modifications are evaluated by ventilation engineers and reflected in updated models and surveys.
In summary, a ventilation tunnel is an underground passage designed mainly for air movement. In mines and other underground facilities, it forms an essential part of the ventilation system, providing controlled intake or exhaust routes that support safe and efficient operation.
