5.Ventilation and Environment department
The primary purpose of tunnel ventilation is to maintain air quality under normal operating conditions: this is known as “normal ventilation”. In the event of a fire, the ventilation system also serves to protect users from smoke and enables emergency and firefighting services to intervene: this is known as smoke extraction. The Ventilation and Environment department conducts research and carries out engineering operations and expert appraisals on both of these aspects.
The environment in close proximity to a tunnel is susceptible to air and noise pollution. The department is involved in both of these issues, as well as the broader question of the overall environmental impact of tunnels, through the analysis of the life cycle of ventilation equipment.
The Ventilation and Environment department’s activities mainly cover the following three areas:
- tunnel fires and explosions,
- smoke extraction,
- environmental and air quality issues.
The department’s main activities in each of these areas are presented below and concern road, rail and urban guided transport tunnels.
Fires and explosions
Fires remain highly feared in tunnels. In recent years, the risk of explosion has also had to be taken into account due to new propulsion energies, in particular natural gas and hydrogen.
In the field of fires, the Ventilation and Environment department is involved in the study of fire sources, propagation and firefighting means (water networks, water mists, water curtains, air or mechanical curtains, etc.).
The department is considerably involved in research on these different aspects, which has enabled it to acquire acknowledged expertise and produce guidelines for the tunnelling profession.
More recently, the development of new propulsion energies, particularly natural gas and hydrogen, has led the department to conduct research on the risks of explosions in tunnels and underground structures and their modelling.
Smoke extraction
In terms of smoke extraction, the Ventilation and Environment department is involved in both the study of physical phenomena and the definition of strategies to be implemented for the design, installation and operation of ventilation systems.
In this area, the challenge for CETU today is to develop solutions that reduce investment costs by optimising the sizing of smoke extraction systems in new projects and improving the efficiency of existing systems. However, these actions must always ensure compliance with the high level of safety required by regulations.
Environment and Air Quality
The very broad topic of the environment is addressed by each of CETU’s departments within their own areas of expertise. The Ventilation and Environment department works specifically on air quality inside and nearby tunnels, as well as on the life cycle assessment (LCA) of ventilation equipment.
With regard to the air inside tunnels, the Ventilation and Environment department is involved in developing a methodology for calculating vehicle emissions to measuring the actual levels encountered in tunnels, including the choice and design of ventilation systems, the implementation of pollution sensors and the study of ventilation control algorithms.
With regard to air quality in close proximity to tunnels, the department has extensive expertise in studying the impact of tunnel emissions: on-site measurements, numerical modelling calculations, and assistance on impact reduction measures. It is particularly active in the development and implementation of tunnel pollution control measures that enable compliance with regulations while keeping the electricity consumption costs of normal ventilation at a reasonable level.
Contact us
Secrétariat : (+33) (0)4 72 14 34 10
Courriel :
Ventilation-environnement.cetu@developpement-durable.gouv.fr