Ventilation Systems for Tunnels and Metro NetworksVentilation Systems for Tunnels and Metro Networks

As the construction of underground tunnels for roads and railways, and for metro networks, has multiplied, Zitrón has increasingly been chosen as the preferred supplier of the ventilation systems that such infrastructure demands, during both the construction and operational stages, to ensure the safety of workers, commuters and all users alike.

Types of Ventilation

Temporary ventilation

The construction phase of underground infrastructure exposes workers to high levels of dust and potentially toxic gases, and demands a ventilation solution that ensures worker safety, whilst minimising costs. Zitrón’s products are tailored to deliver these outcomes and to adapt to the constantly changing parameters of the construction environment.

Permanent ventilation

Once operational, underground infrastructure  – be it road or railway tunnels, or metro networks –  requires ventilation solutions that are 100% reliable and effective in maintaining the supply of fresh air and that, with the proper maintenance, will continue to do so over the long lifespans of each asset. Zitrón’s expertise, products and solutions make it the trusted ventilation partner to guarantee user safety and maximise asset utilisation.

Ventilation Systems


Of all underground transport infrastructure, metro systems tend to have the most demanding ventilation requirements because of their extensive network of long tunnels and very high usage levels. Safety and reliability are therefore of paramount importance. Zitrón’s credentials in meeting the demanding requirements of metro systems are second to none and are the reason why we have been entrusted to supply the ventilation solutions for most of the world’s major metro systems.


Road Tunnels

Motor vehicle emissions are a key source of air pollution and mean that tunnel size and traffic flow are critical factors in the design of ventilation systems for road tunnels. Zitrón’s many years of experience in this area means that we can design and supply ventilation solutions that ensure the availability of sufficient air flows within a tunnel under all traffic conditions and in the event of emergency situations. Our solutions are tailored to each project, to deliver in-tunnel air quality and control emissions from portals.

Railway Tunnels

The way in which tunnels are ventilated is one of the key considerations when planning and designing an underground railway (road or metro). Ventilation systems must comply with very strict regulatory criteria, and be capable of controlling passenger comfort and dealing with large amounts of smoke in emergency situations. Zitrón is at the forefront of designing and supplying ventilation systems that deliver the most demanding of comfort and safety levels.

Fan Types

Axial Fans

According to the specific tunnel conditions, we can design and manufacture axial fans that are configured either horizontally or vertically. Our expertise allows us to offer fans for all operating environments, whether they be the horizontal fans traditionally preferred for tunnel ventilation systems or the vertical fans that are increasingly being chosen to optimise the available underground space.

Jet Fans

In longer tunnels, jet fans play a vital role in effective air circulation, including drawing in additional air during periods when traffic flow has slowed down. These fans offer improved flexibility and lower costs compared to transverse and semi-transverse ventilation systems that use axial fans. Our jet fans are manufactured to handle the highly corrosive conditions found in tunnels and to deliver reliable performance over their lifespans.

Related links

CFD simulations


Zitrón’s ventilation solutions are custom made, using the latest software and know-how, to identify potential improvements and deliver the most efficient designs for each installation.

Quality Control & Verification


We use cutting-edge 3D scanning technology and other tools to ensure product quality and performance.

Monitoring & Control Systems


Monitoring of ventilation system performance is made possible by means of data acquisition systems that enable continuous analysis and provide alerts as regards maintenance requirements.

Factory Acceptance Test


Zitrón’s investment in quality assurance, by building one of the world’s largest test benches for underground ventilation fans, allows us to offer our customers complete Factory Acceptance Testing (FAT) of their fans.

Damper systems


Zitrón’s extensive know-how and manufacturing capabilities mean that we can design and manufacture dampers to meet all customer specifications.

Mobile Work Platform


Knowing that time is money and that safety is paramount, we have designed a Mobile Work Platform to facilitate the installation and maintenance of ventilation systems in tunnels.