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The striking form of the Allianz Arena in Munich has quickly become a footballing landmark. But the unusual structure meant many deviations from conventional fire safety building codes.
It was something of a minor miracle that in a period of weak economic growth and empty public purses, the Allianz Arena just outside Munich went up in just three years. The new stadium has already become a footballing landmark with its unique outer shell, which lends it the affectionate nickname, the ‘rubber dinghy’.
Everyone involved understood right from the start that safety would be singularly important in such a project. The Munich Municipal Fire Department was involved in the planning process from day one, and was able to voice its concerns before each phase of the plan was implemented. Because of the stadium’s unusual position in a corner between two motorways and the resulting problems with limited access, the fire brigade put forward specific demands as early as during the outline area development planning process:
– Emergency vehicles required dedicated roads around, to and from the stadium, which had to be separated from the streams of visitors and could not be obstructed by spectators.
– Relief units had to be able to reach the stadium even if there was traffic congestion on the access roads.
– Provisions had to be made to allow the safe evacuation of injured people on the ground
– Provisions had to be made to allow patient transport by helicopter.
Safety routes
In the end, this led to the construction of a dedicated road network, which is still reserved for exclusive use by the police and emergency services – despite frequent requests by other parties. A number of points were raised during the specific planning phase. These were based on the following requirements. Substituting structural and technical fire protection measures by organisational or operational measures was not an option. Any requirements of the med
ical and civil protection services had to be included, even in the absence of any legal obligation. Potential risks had to be rigorously examined, even when their probability of occurrence was low (e.g. video wall fires, fires in the loudspeakers beneath the stadium roof, storage of materials in locations reserved for other purposes, etc).
The stadium was designed as a separate building with an underground car park and an adjacent multi-storey car park. The following building parameters were implemented:
– The Multi-storey car park has a footprint of 560m x 140m and four parking levels with 9,800 spaces. There is spectator access from the roof of the car park to level 2 of the arena.
– The stadium has a footprint of 259 m x 225m and is 52m high. It contains 66,000 seats on three levels including 110 boxes with 1300 seats. It also houses 1200 additional VIP underground car park spaces, and restaurants with a total of 3700 seats.
The unusual design of the car park, which includes a roof used as an esplanade, required the development of a new smoke venting plan. This involves the use of smoke venting systems to extract the smoke to the outside, via light wells which come up to the roof of the car park at ground level. The provisions of the building for regulations for car parks apply in all other respects.
Tough decisions
The discussions concerning the actual stadium building turned out to be far more complex. Following a long debate on the principles of the project, the construction of a dedicated football stadium was given preference over a universal event arena with a full roof. This outcome meant that the strict provisions of the building regulations on places of assembly did not apply.
An innovative facade consisting of inflated membrane cushions, which give the stadium its distinctive look, and its deviation from general building regulations presented a big challenge to fire protection. The plans for the facade alone violated the following building regulations:
– Non-flammable external wall cladding
– Non-flammable roof
– Hard roof
– Non-flammable suspended ceiling
– No parapets or aprons in accordance with the high-rise building guidelines
– Double facade
As a result, the fire department focused on the design of escape and rescue routes, on automatic early fire detection or sprinkler activation in areas at risk, and on the membrane cushions of the facade. The calculated total exit widths specified in the regulations for places of assembly were applied to the rescue routes. For internal areas this is 60cm per 100 persons, and in the Stands, 60cm per 300 people. The following fire protection devices were installed: almost 20,000 sprinkler heads; 300 wall hydrants; 35,000 automatic linear fire detectors and 4600 push-button fire alarms.
The combustion behaviour of the membrane cushions was examined in a series of component tests carried out at MFPA Leipzig GmbH. These included a simulation of a car fire in front of the cushion facade (see figure), a simulated car fire between the cushion facade and the glass facade, deliberate fires, and a total room fire (with a sprinkler system failure) and resulting in fire spreading to the outside.
Other structural measures included: the verification of the steel construction of the roof by calculation (roof structure with a clearance > 5m ; otherwise it would need an 30 minutes’ fire resistance coating ); the protection of all systems and installations below the roof (video walls, loudspeakers, floodlights, cable and tube systems, and control cabinets); the protection of the external wall of staircase on the side facing the double facade with 30 minutes’ fire and radiation protection.
In addition, the following resources are based at the stadium during every game, depending on the number of tickets sold:
– Firefighters with auxiliary fire tenders
– Medical services – up to four doctors depending on the number of spectators and up to 48 paramedics
– Seven medical stations each with an emergency equipment
– Up to 505 security guards
– Police, again with numbers depending on the number of spectators
Announcements
A separate safety plan, which includes different scenarios based on four levels of severity, was developed. The measures are specified in a checklist. The stadium was divided into a total of 12 zones for the purpose of evacuation. These zones can be evacuated individually or simultaneously. Specific loudspeaker announcements, which are made live by staff rather than being recorded, were developed for each measure in consultation with psychologists. Over 6200 loudspeakers cover the whole area of the stadium.
Conclusion
The construction of the Allianz Arena led to the implementation of a modern risk prevention and safety plan, making it one of the safest stadiums in Europe.
Wolfgang Schauble, is a professional engineer and head of the Munich Municipal Fire Department. Contact: bfm.leitung.kvr @muenchen.de