Halton’s Success in the Tunnelling Sector

Tunnel infrastructure—whether for roads, railways, metros, or utilities—presents some of the most demanding environments for mechanical systems. In enclosed underground spaces, ventilation is a critical safety system, supporting air quality during normal operation while also contributing to smoke management and emergency response.

Tunnel ventilation equipment must therefore be designed to withstand demanding operating conditions, including:

• Stringent fire and smoke safety requirements
• High temperatures and pressure fluctuations
• Low-leakage requirements
• Corrosive or harsh environmental conditions
• Space constraints requiring project-specific engineering

The performance of individual ventilation components, particularly dampers, can directly affect airflow, smoke control, and the overall reliability of the system.

Halton combines ventilation engineering expertise with purpose-designed damper solutions for demanding tunnel and metro applications. Its tunnel ventilation portfolio includes high-temperature tunnel dampers, fire dampers, airflow management dampers, pressure-relief dampers, and other solutions designed for underground infrastructure.

These solutions are developed to address both normal ventilation requirements and emergency conditions, where reliable airflow control and smoke management become critical.

Key solutions include:

• High-temperature tunnel dampers, such as the CFD-02TM
• Fire and smoke dampers
• Airflow management and balancing dampers
• Pressure-relief dampers
• Customised damper configurations for space-constrained installations

The CFD-02TM, for example, has been tested for operation at 400°C for two hours and for repetitive pressure loading up to 6,000 Pa. It has also undergone fire endurance testing in accordance with UL 555 and BS 476 Part 20.

Tunnel ventilation requirements vary considerably depending on the type of infrastructure, operating conditions, available space, and applicable safety standards.

Halton’s tunnel and metro experience includes projects across Europe, the Middle East, and Asia. Its published project references include the Riyadh Metro, Crossrail, Heathrow Express, the Mont Blanc Tunnel, and several other road and metro infrastructure projects.

This experience provides an important engineering foundation for addressing the different requirements encountered in underground infrastructure projects.

For example, Halton has highlighted its experience supplying CFD-02T tunnel dampers for the Riyadh Metro, where more than 300 units were used. The project demonstrates the importance of combining high-performance equipment with project-specific engineering and installation requirements.

Tunnel ventilation systems are often installed within highly constrained spaces. Standard equipment dimensions, actuator positions, pressure requirements, and airflow characteristics can create challenges when integrating dampers into the overall system.

For this reason, customisation can play an important role in achieving the required ventilation performance.

Halton’s tunnel dampers can be configured to maximise free area, optimise airflow, and minimise pressure loss. The company also manufactures certain tunnel dampers in fine dimensional increments and allows flexibility in actuator positioning, helping equipment adapt to project-specific layouts.

Other important considerations include high-temperature performance, pressure resistance, leakage control, testing and certification, space optimisation, energy efficiency, and long-term reliability. These factors allow engineers to evaluate damper solutions not only according to their basic airflow function, but also according to the specific operational and safety requirements of the tunnel.

Tunnel ventilation equipment must continue to perform under conditions that may include high temperatures, pressure surges, repeated operation, and restricted installation environments.

Halton’s published testing for tunnel dampers includes high-temperature operation, leakage testing, mechanical resistance, pressure-differential testing, operational speed, and lifecycle testing. The CFD-02TM, for example, has undergone 100,000 automatic operating cycles and testing for repetitive loading at 6,000 Pa.

These tests are particularly relevant to tunnel applications because ventilation equipment may be required to operate reliably during both everyday service and emergency scenarios.

In normal operation, tunnel dampers help regulate volumetric airflow and control ventilation throughout the tunnel. During a fire, appropriately designed dampers can support smoke extraction, isolate sections of the ventilation system, and help limit the spread of smoke and hot gases.

The Middle East continues to invest in major metro, road, and underground infrastructure projects, creating demanding requirements for ventilation systems operating in challenging environmental conditions.

Tunnel ventilation equipment in the region must account for project-specific factors such as high ambient temperatures, demanding operating schedules, restricted installation spaces, and the applicable fire and safety requirements.

Halton’s experience in projects such as the Riyadh Metro, combined with its customised tunnel damper solutions, demonstrates the importance of engineering equipment around the actual requirements of each infrastructure project rather than relying solely on standard configurations.

Tunnel ventilation cannot be considered as a collection of individual components. Dampers, fans, ductwork, controls, smoke extraction systems, and other ventilation elements must work together as part of an integrated system.

For this reason, damper selection should consider more than basic airflow requirements. Engineers must also evaluate temperature resistance, pressure conditions, leakage, actuator configuration, installation space, maintenance requirements, applicable standards, and the expected operating conditions of the tunnel.

Halton’s tunnel solutions are developed around this principle, combining product engineering, testing, customisation, and application knowledge to address the specific requirements of underground infrastructure.

As road, rail, metro, and utility tunnels become increasingly complex, ventilation systems must deliver reliable performance under both normal and emergency conditions.

Effective tunnel ventilation requires careful consideration of airflow, smoke control, fire resistance, pressure, leakage, space constraints, and long-term reliability. High-performance dampers form an important part of this system by controlling airflow during normal operation and supporting smoke and fire management during emergencies.

Through its tunnel ventilation solutions, testing capabilities, and project-specific engineering approach, Halton provides technologies designed to address the demanding requirements of modern tunnel infrastructure. The result is a ventilation strategy focused not only on airflow, but also on safety, reliability, maintainability, and long-term system performance.