What is Ventilation of tunnels? Explain types of ventilation briefly

Ventilation of tunnels: During tunnel construction, various ventilation systems are provided to remove the dust and poisonous gases. The tunnel construction work is usually carried out by blast ad drill method, which have many safety and health issues due to the dust and chemicals involved in ballast causes poisonous gases.

The main objective of the ventilation of tunnels are:

• To provide the environment of fresh air for the workers.

• To exhaust out the harmful gases which are injurious to health.

• To remove the blasting and drilling gasses emitted.

Ventilation in tunnels during and after construction plays a very important role such that tunnel should maintain the comfortable and safe environment for the tunnels.

Types of ventilation systems:

• Longitudinal Ventilation Airflow System in tunnels – In this type of ventilation system, the airflow direction inside the tunnel is longitudinal in nature. At the entry of tunnel, these airflow with fresh air moves inside the tunnel and pushes the pollutants gasses and effluent with them. And in the exit of the tunnel, the pollutant gases are discharged.

• Natural Ventilation systems in tunnels – When there is the provision of the drift in the tunnel between one end and other, then it forms a fair ventilation. This system of ventilation is useful only in case of the short tunnels.

• Mechanical Ventilation System in tunnels – In this type of ventilation system, mechanical devices like electric fans, blowers, etc. which serves the function of removing the exhaust gases within the tunnel and help in the movement of fresh air inside the tunnel.