Tunnel hoods to be used for first time on Mumbai-Ahmedabad bullet train project

MUMBAI: The Mumbai-Ahmedabad Bullet Train project will become the first railway project in India to use tunnel hood technology at mountain tunnel portals to reduce noise and improve the aerodynamic performance of high-speed trains.The bullet train corridor passes through challenging terrain and includes seven mountain tunnels in Maharashtra and one in Gujarat. Tunnel hoods will be installed at both ends of these tunnels.When a high-speed train enters a tunnel, it pushes a large volume of air ahead of it, creating pressure waves. If these are not controlled, they can generate a loud “tunnel boom” when the train exits the tunnel.Officials said the tunnel hoods act as a transition zone between the open environment and the tunnel, allowing air to enter and exit more graduallyThis helps reduce sudden pressure changes, lowers noise levels and improves the overall aerodynamic performance of the system.The structures are also expected to minimise disturbance to nearby communities and support the safe operation of trains travelling at speeds of over 300 kmph.A key feature of the tunnel hoods is the provision of specially designed pressure-relief openings or vents. These allow part of the compressed air to escape gradually into the atmosphere as the train enters the tunnel, reducing the intensity of pressure waves and ensuring smoother airflow.

Tunnel hoods are widely used on high-speed rail networks across countries operating bullet trains.Their adoption on the Mumbai-Ahmedabad corridor brings international engineering practices to the project, with the aim of improving safety, passenger comfort and environmental performance.