history, architecture and construction of the hall

The year was 2001, and the then director of Sazka, Aleš Hušák, was looking for ways to build a new hall for the 2004 Ice Hockey World Championship in Prague in a short time. pushed away.

The IIHF hockey federation insisted on a new hall in the capital, and if the Czech Republic did not have time to build it, it would be a disgrace and probably lose the opportunity to host this prestigious event in future years as well.

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An unthinkable situation for many. At that time, the Czechs lived in the euphoria of the victory in Nagano and the hat-trick of three gold medals in a row at the World Championships. The national sport was at its historical peak and the enthusiasm opened the door to quite challenging and risky possibilities.

The management of Sazka, led by Hušák, then offered themselves as the saviors of the situation and convinced the hockey officials that they were the safest investors. The retired ČKD Lokomotivka factory on the border of Libna and Vysočany, directly below its headquarters, was chosen as the site for the construction. Due to the construction of the hall, the owners of Sazka – the sports associations – founded the company Bestsport.

Regarding the design of the arena, representatives of Sazky approached the architectural and engineering firm Atip from Trutnov, which was led by designer Vladimír Vokatý and his son Martin Vokatý, an architect and former top skier. The reason was good experience with cooperation from earlier projects.

However, this was not a situation for hesitant shooters, it was about speed. “The time to decide whether to participate in the project is still one of my funniest stories. We were given about 30 minutes to make a decision,” recalls Martin Vokatý with a smile.

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At that time, there was no similar hall in the Czech Republic, so it was necessary to find inspiration abroad. “The investor very wisely organized several study trips both to Finland, where they had the latest Hartwall Arena at the time, and especially to the USA, where we gathered information about the operation and technical solutions of similar complexes,” explains architect Vokatý.

The result was a plan to build a hall as part of the multi-functional complex Zelený ostrov. Next to the arena with the tentative name Hala Sazka, another smaller one was to be built as a training room, a hotel, a business and entertainment center, a parking garage and office space. Part of the complex was to be covered by a roof park, which gave the project its name.

The high-tech design of the hall itself is an original solution by Atip. The main expressive element has become the construction projecting the glass facade, which, in combination with the silvery aluminum cladding, gives the hall the appearance of a glass palace.

Photos of the O2 arena during construction and today

Vokatí invited specialists from Excon to help with the roof design. “We founded the company back in 1990, and in 2002, when we got to the project, our team of structural engineers in the field of steel structures was probably the strongest in the Czech Republic, with many references. We accepted the offer as a challenge, and that without hesitation,” describes structural engineer Vladimír Janata, who is an expert in the field and led the entire project.

Martin Vokatý designed the hall as circular, with a roof in the shape of the top of a sphere or spherical canopy. This requirement led Vladimír Janata to an original design solution that no one had used before.

“If you imagine the top of the globe cut off by, say, the Arctic Circle, then I placed the 36 main beams in the direction and shape of the meridians and the circular stiffeners in the direction of the parallels. In addition, I designed the main beams as so-called braces, consisting of compressed lattice beams in the upper part and tensioned prestressed rods in the lower part, which are also an interior decoration,” explains Janata.

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Architect Vokatý designed the interior in such a way that people could spend time in the hall outside the main event. That is why he also placed shopping arcades and spaces for other services inside. He divided the seats for spectators into three circuits. The first for 17,000 people in ordinary seats with the appropriate facilities and a restaurant, the second with places at tables overlooking the area and the third with boxes and VIP lounges or skyboxes on a separately accessible floor.

Although there were difficulties with financing and land, the actual preparation, design and construction work went smoothly. “During the preparation of the project, it could be seen that the construction of the hall became a kind of ‘national interest’ and all those involved, i.e. the investor, officials and designers, chose paths leading quickly to a successful end,” says Martin Vokatý.

The only major change in the designs occurred after the terrorist attack on September 11, 2001. The entire project had to be reworked in terms of all security solutions and systems.

Structural engineer Vladimír Janata reminds us that no complications were allowed during the construction, otherwise the holding of the championship would be in jeopardy. The arena had to be completed in a record time of less than a year and a half. “Therefore, in addition to a thorough inspection of the drawings, we very carefully prepared the assembly and tensioning procedure for all 36 tensioner rods. The construction behaved perfectly, exactly according to the model from the computer. In addition, we were constantly on the construction site and caught any minor discrepancies in the bud,” Janata explains.

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The hall with the original name Sazka Arena was built and successfully put into operation on time. It was the first of its kind in the Czech Republic, and thus became a model for the creation of decrees and regulations for building similar domestic arenas. “For example, fire or hygiene regulations have become significantly more precise thanks to this multifunctional hall,” points out Martin Vokatý. In addition, the hall received the prestigious Building of the Year award in 2004, and the roof itself received an award from the Chamber of Engineers and the Academy of Engineering of the Czech Republic and the European Steel Design Award.

For Vladimír Janata and Excon, the roof of the arena was the first large construction with pre-tensioned rods and started a number of other projects using pre-tensioning, a technology better known for bridges. “These structures have many advantages. Compared to standard solutions, they bring significant savings in weight and price, so in modern terms they reduce the carbon footprint. In addition, they also brought interesting innovative solutions to architects, which is why many people like to work with us,” praises Vladimír Janata.

The team from Excon used pre-tensioned rods to roof the Werk Arena in Třinec, the hockey stadium in Kladno and the arena in Chomutov. He also applied preload in the design of a hangar in Mošnov, several glass atriums of buildings, the Trojský most in Prague and in the conversion of a gas-powered concert hall Gong in Ostrava’s Dolní Vítkovice. “The Sazka Arena principle was used, for example, by the designers of the Olympic stadium for table tennis in China, they cited Sazka as a model they followed,” highlights Janata.

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Even today, he would not change anything about the construction of the Prague arena. Martin Vokatý, who is in contact with the operators, also perceives the hall and its functioning positively even after 20 years. A high-quality project team and state-of-the-art technology met here together with an investor who approached the preparation of the building and the future filling of the hall in an enlightened manner.

“The arena was created at a time when some solutions and materials were not even known in Europe, and it was solved with the help of subcontractors from the USA. For example, the final floor covering, which has been used for 20 years and is still of high quality, comes from the USA,” explains Vokatý.

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Other buildings gradually grew around the arena, including the neighboring smaller congress hall O2 universum, which was also designed by the Atip studio. The investor and the owner of the hall and part of the plans have changed, but today’s appearance of the area largely corresponds to the initial ideas about the Green Island, including the green roof of the shopping center.

“The only contradiction is that the originally planned greater connection of objects, including spectator access from the parking garage, did not take place. This is the only thing that I would keep from the original solution and add to the current state,” says Martin Vokatý.

The construction of the arena and the collapse of Sazka

This year, at the end of March, the hall under today’s name O2 arena celebrated its 20th anniversary. Design has become simpler and faster during that time, for example in the field of technology. “There are wireless data transmissions, so there is no need for large-scale coordination when conducting electrical routes. There are also much more durable materials from which the final surface treatment of individual surfaces is designed,” compares architect Vokatý.

Vladimír Janata also mentions the development of software, from the 2D display at the time to today’s generation of drawings from 3D models. “Nowadays, computer technology helps us with significantly faster calculations, for example, instead of two hours, the calculation time is two minutes,” adds Janata.

Photos of the O2 universum congress hall

Digitization of constructions, known by the acronym BIM, also began, which simplified many things and eliminated the collision of individual professions that used to happen in projects. However, as both Vokatý and Janata agree, BIM has complicated some things. Therefore, according to Martin Vokatý, the overall time to manage the projects has not changed much. “However, what has changed a lot is the time it takes to get permission to build such a hall. From today’s point of view, it seems completely unrealistic to obtain all permits for such a construction in the course of a single year, as was possible in 2001,” comments the architect.

For proposals for similar halls, Martin Vokatý sees it as a necessity to always thoroughly consider the capacity and carefully calculate the possibilities of use, including the real number of events, as well as traffic accessibility and slope. According to him, it makes no sense to think about building a hall only for hockey, every similar arena in the Czech Republic and abroad should be multifunctional.

The speed of interior transformation from sports to cultural and other uses and vice versa is also important. “At today’s price of construction work, the economy of operation must come first. And that is exactly what I miss in many projects in the Czech Republic. From this point of view, there is no doubt that the hall in Brno is well managed, even if it will be difficult to operate the hall there as well,” thinks the architect. Vladimír Janata and the Excon team are also working on the design of the roof of the arena at the Brno exhibition grounds.

Vokatý considers the planned hall in Jihlava to be architecturally successful. He himself designed the reconstruction of the winter stadium in Zlín, where he also used his experience with the auditorium and VIP boxes in the O2 arena. However, this project was stopped by covid and the subsequent increase in prices in the construction industry. Nevertheless, Vokatý hopes that the project will be realized in time. “It is always better, if possible, to use the existing hall or at least its place for reconstruction than to build a new one on a green field, because the running costs will subsequently be added to the city,” concludes the architect.