As urbanisation accelerates in South Africa, the demand for tunnelling is growing, driven by the need for sustainable public transport systems and expanded water infrastructure. While large-scale tunnelling projects remain limited locally, projects like the potential expansion of the Gautrain network and upgrades to the country’s bulk water infrastructure highlight a growing need for sophisticated tunnelling solutions. At the heart of these projects are advanced ventilation systems, which are critical for ensuring worker safety, operational efficiency, and the functionality of underground tunnel networks. Drawing on ventilation expertise developed in industries like mining, innovative solutions can be adapted to support the sustainable development of future urban infrastructure networks across the country.
Continued urban growth, driven by rural-urban migration in South Africa, will undoubtedly require additional public transport infrastructure, bulk water supply, sanitation, and energy systems, many of which depend on sophisticated tunnelling and ventilation solutions. Projects like the recent Gautrain and the Lesotho Highlands Water Project, developed in 1990, have set benchmarks for efficiency and safety, and future expansion of these and similar projects will demand equally innovative approaches.
In tunnelling environments, ventilation and cooling systems are essential in managing underground temperatures and controlling air quality. By circulating fresh air and removing potentially harmful gases, dust, and fumes, these systems ensure compliance with health and safety regulations while safeguarding worker well-being. Much like in the mining sector, where insufficient airflow rates can constrain operations and reduce productivity, effective ventilation in metro tunnelling is fundamental to the success of a project. It supports tunnel and chamber construction while maintaining compliance with health and safety standards throughout the project lifecycle.
Metro tunnels require ventilation and cooling during both construction and operation. During construction, these systems remove contaminants from vehicles and equipment, while in operation, they maintain air quality to protect workers and commuters. Strategic planning and the innovative use of technology are essential to designing systems that meet these needs efficiently. Technological innovations are driving advancements in ventilation systems. This includes inlet guide vanes on fans to ensure optimal flow and pressure, energy-efficient variable speed drives for fan motors, fan staging to regulate air pressure in ducted tunnels, and real-time air quality monitoring through sensors together with human operator oversight and management.
Additionally, the use of ventilation districts to segment ventilation to specific independent working areas or zones during tunnel or chamber development use jet fans to direct air where needed in often very large caverns ranging from 50m2 to 4800m2. These innovations not only improve worker health and safety and functionality but also enhance energy efficiency and sustainability.
By prioritising metro tunnelling as part of urban transport planning, transit systems such as the Gautrain can help reduce reliance on carbon-emitting vehicles, significantly lowering urban carbon footprints while laying the foundation for sustainable urban growth. Effective tunnelling and ventilation solutions not only contribute to safer and more efficient infrastructure but also align with broader goals of environmental responsibility and urban resilience.
As South Africa prepares for future urban infrastructure to alleviate pressure on its existing systems, innovative ventilation solutions will be crucial. These systems will enable safer, more efficient and more sustainable development of critical urban infrastructure, thus shaping a greener, more responsible built environment.
[By Marle Hooman, Principal Ventilation Engineer at BBE Group Australasia]
