Lille stadium: fire safety different from the others

Credit: Valode & Pistre architects

A full roof over a stadium is an architectural innovation in France.  A stadium of this type is no longer an open air structure in the sense defined in the typology of Public Assembly area (ERP) standards and is more akin to a theatre.  The North Department CCDSA (Commission Consultative Départementale de Sécurité et d'Accessibilité – Departmental Safety and Access Consultative Commission) examined the questions of the class of the establishment and smoke removal from it when its roof is closed.  Furthermore, the Euro 2016 Large Stadiums commission report proposed to examine the creation of a new type of Public assembly area taking account of the specific features of the future closed-roof stadiums, or to adapt existing regulations due to the lack of any reference information (see inset).

The half-closed North side of the stadium during wind testing (pressure measure on the envelope)

For the Lille Urban District project (architects Valode & Pistre, Atelier Pierre Ferret), CSTB studied conditions for smoke collection and smoke removal in the 50-meter enclosure and rooms in the grandstands, for Eiffage TP (Public Works contractor).  "We carried out digital simulations to determine whether or not smoke could be evacuated through the roof extraction system" says Philippe Fromy, Fire Safety Engineering Expert.

A mobile part of the stadium will house a theatre located in the infrastructure.  Various fire scenarios adapted to the different activities and configurations of the stadium have been simulated to determine whether or not smoke that collects under the roof might descend to the highest level of the grandstands, thus hindering evacuation of spectators.  This smoke collection scenario seemed probable, and consequently a natural smoke removal solution was designed.  Results of the study will be presented to the CCDSA in April 2009.


Ten configurations for wind tunnel tests

North side of the stadium, with a drill for comfort study

Tests on mock-ups were also carried out in a boundary layer  wind tunnel in Nantes, designed to measure wind actions on the structure;  more particularly quasi-static forces and the dynamic behaviour (for example the behaviour of the main beam under tension/compression).  Considering the modularity of the stadium (partial or complete closing of the roof), ten configurations had to be tested for the four mobile roof elements.  "We also measured comfort under wind, to check the well-being of spectators.  The wind speed must be less than the maximum speed acceptable to spectators," says Marc Dufresne, aerodynamics expert at Nantes CSTB.  The results analysis is transmitted to the Greisch design office, which can then design sections of structural elements.  Since stadium facades are permeable, the wind effects simulated in Nantes will also be used in the smoke removal engineering study for the structure, to provide the air inlets necessary for natural smoke removal.  

Work on the Lille Urban District Stadium will begin in mid-2009, and delivery is planned for 2012.  No doubt, it will be a precursor for other closed-roof stadium projects.

No new type of Public assembly areas …, but rather a support mission

Subsequent to the Seguin report, the Ministry of the Interior responsible for fire safety regulations for Public assembly structures has set up as a working group in which CSTB participates.  This group has undertaken to revise the regulations for PA (open air) type areas and consolidate them.
The Central Safety Commission (CCS) recently decided to create a support and advisory mission to CCDSAs, with the objective of creating a document containing the different measures for adaptation of existing rules to very large multi-purpose sports facilities.