Visualisation of a metro station with incoming train

Rail and Metro Tunnel Ventilation

Operation of rail tunnels, metro systems or underground tramway lines may require tunnel ventilation for several purposes like maintaining air quality and air temperatures, providing tenable conditions during cold or hot incidents and keep cross-passages and the non-incident running tunnel free of smoke.
Experienced IP Engineering staff is specialized in all relevant railway and subway tunnel ventilation domains and considers beside legal and standard basics operational aspects, rolling stock characteristics and experience from historical incidents as well as operation experience – we offer a comprehensive best practice approach.
Physical modelling and measurements are part of our daily work for all aspects that require deep physical understanding, such aero- and thermodynamics of underground facilities.

Tunnel Specific Requirements

For metro and rail tunnels four major operation modes need to be considered with different requirement and objectives:
- Normal Operation,
- Congested Mode Operation,
- Emergency Operation and
- Ventilation for Maintenance Work.
Boundary conditions and input data for accurate assessments for all modes have a broad bandwidth such as rolling stock, tunnel climate, passenger loads, civil structure of tunnels and station boxes architecture of stations, signalling system, rock data, etc..
Beside good engineering practice, operational experience and up to date state of technology, standards, laws and guidelines play an important role in the design of ventilation systems for subway and rail tunnels. Such as the American NFPA 130 or European guidelines as e.g. the German Technical Rules for Trams – Fire Protection in Underground Operating Systems or e.g. the French standard Arrêté du 22 novembre 2005 relatif à la sécurité dans les tunnels des systèmes de transport public guidés urbains de personnes. Particular emphasis is placed on sustainability aspects for the planning and operation of tunnel safety equipment.

Diesel Powered Freight Trains in Tunnels – Operational and FLS Aspects

Several issues associated with operating Diesel powered freight trains in tunnels are of high importance during the planning and operation phases. During uphill operation, high air temperatures at air intake locations of diesel trains might reduce diesel motor efficiency (choking). In a fire scenario, ventilation can exacerbate the firefighting efforts due to fanning or water-reactive cargo materials and their chemical reactions with water. Services focus on air quality in diesel train-operated tunnels, the impact of freight trains on the tunnel safety concept, and on strategies to overcome heat issues at locomotives air inlets.

Designing the Ventilation Systems

The layout process of tunnel ventilation strategy and equipment is of crucial importance for the general acceptance of new rail tunnels and subway projects. IP Engineering solutions are based on experiences, the best practice approach and the fundamentals of fluid dynamics and thermodynamics and comply with legal and standards requirements.
Our experts provide solutions for reliable railway and metro tunnel ventilation system design for all project stages. Additionally, we take care about tendering, testing and commissioning phases and accompany operators for all questions and issues raised during operation phases.

Calculations and Simulations

Analytical and numerical modelling of rail aerodynamics and thermodynamics for tunnel climate, ventilation and smoke extraction systems, including the effects of traffic, ambient weather and tunnel fire are carried carefully out.
IP Engineering provides numerical modelling services with internationally recognized numerical software tools for 1D and 3D aerodynamic and climate assessments but as well broadly in-house developed analytical tools for special tasks, e.g. temperature analysis of load bearing structures, pressure comfort analysis for passengers on board, etc..

Interfaces to neighbour domains

Several major interfaces need to be coordinated for the metro tunnel ventilation layout design process, such as: architecture, civil-engineering, fire and life safety, pedestrian modelling, rail operation and signalling, control systems and implementation, emergency procedures, evacuation, electrical engineering, geology, maintenance, RAMS, further equipment like Platform Screen Doors, cross-passage ventilation and cooling, investments and operational costs.
IP Engineering has vast experience to serve and integrate requirement from neighbour domains during the layout process of the ventilation system.

Procurement Support and Site Supervision

IP Engineering experts have vast experience for procurement and commissioning of all tunnel ventilation related equipment and for site supervision when installing.
Beginning with the performance schedule and the bill of quantities, we take care about relevant test specifications for factory acceptance tests (FAT), site acceptance tests (SAT) and integral safety tests (SIT).

Safety in Long Rail Tunnels

Long rail tunnels pose particular challenges in emergency situations due to the prolonged time required for engaging rescue forces at a site of an incident. To ensure the health and safety of passengers and staff, advance planning and later operation of rail tunnels and their facilities must implement special standards to prevent incidents. Prevention has the highest impact on the level of safety and is the most effective measure. Mitigation measures help to limit the impact of an incident on the rail infrastructure, while evacuation measures help passengers and staff. Rescue measures support rescue teams to carry out their work in an emergency. Facility safety measures are determined based on the operational concept implemented, while rolling stock plays a key role in tunnel safety considerations. Communication systems, signage, emergency lighting and handrails, camera systems, and ventilation are all important tunnel equipment.


IP Engineering experts will be at your side for all ventilation related enquires – we support you with specialist counselling – worldwide.


Bernd Hagenah, PhD
Practice leader for rail and metro tunnel ventilation