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Cape Town Stadium, Cape Town, South Africa

1. Introduction

The Cape Town Stadium, situated between Table Mountain and Table Bay, is the most elegant one of all the stadia of the Soccer World Cup 2010 in South Africa. Its curved silhouette elegantly fits into the exposed situation at the Victoria & Alfred Waterfront.

The Cape Town Stadium’s roof structure was built by the Birdair/PFEIFER Joint Venture under the leadership of PFEIFER. Said roof structure is a suspended roof consisting of ring and radial cables as well as radial lattice girders. This sub structure bears the roof cladding consisting of laminated safety glass on a steel grid as well as the translucent membrane in the interior. The space between the glass roof cladding and the membrane integrates technical elements such as the PA/sound system and illumination; in addition it offers protection from bad weather and serves as sound absorbing volume.

The filigree structure distinguishes itself by its high complexity and the enormous number of individual components used in construction. The logistic challenges as well as the required coordination of all parties involved in this type of construction, akin to line construction, taxed the responsible PFEIFER personnel in the extreme. 

The result, however, convinces through its high aesthetic appeal and its elegance and proves that “light cable structures“ are an option also for stadia of this size.

2. The Project

2.1 Overview in Figures

The Cape Town Stadium will offer 68,000 seats on three tiers during the Soccer World Cup 2010. Once the final whistle has been blown, the capacity will be reduced to 55,000 seats. The VIP-area with separate entrance and VIP-club comprises 60 boxes of altogether 2,200 m2. The whole stadium complex was built mainly as an in-situ-concrete structure using altogether 109,000 cubic meters of reinforced concrete. Construction started in March 2007 and was finished by December 2009.

The Stadium Roof in Figures:

Covered Area:38.000 m2
Perimeter of the Compression Ring:800 m
Compression Ring:1,400 tons of steel
Steel Main Structure, Lattice Girders:1,800 tons of steel
Glass Supporting Structure:600 tons of steel
Cable Structure:7,000 m cables, 150 tons of castings
Safety Glass:9,000 individual panes
Membrane:42,100 m2 PVC membrane
Screws:about 250,000 pieces

2.2 The Roof Structure

The cable structure with the integrated steel compression ring along the outer edge is designed like a spoke-and-wheel system. Such spoke-and-wheel systems are often employed for stadium roofs. The compression ring of such a system represents the “rim”, the radially assembled cables serve as spokes and the ring cables represent the hub. These spoke-and-wheel systems are highly pre-tensioned and generally self-supporting. For the Cape Town Stadium’s roof 72 radial cables have been connected to 8 ring cables using cast steel elements. The radial cables, in turn, support steel lattice girders, which are connected to one another via tangentially arranged steel girders. 

The glass panes are individually placed on the steel grid in a freely floating manner, in order to be able to withstand the enormous movement they are subject to. This represented one of the biggest planning challenges due to the fact that the notorious Cape winds cause the roof to oscillate with an amplitude of +/- 1 meter. Due to the roof’s undulating shape, some 4,500 of the altogether 9,000 glass panes are model panes that had to be tailor-made for their respective position in the roof. The membrane spans distances of 8-13 m from radial cable to radial cable across the roof’s length of some 40 m.

All elements were accurately manufactured to dimension in production facilities on four different continents and modularly assembled on the construction site.

2.3 Installation of Cable Structure and Glass Roof

In early 2009, the 700 t cable structure was laid out on the ground in a record-breaking 4 weeks. Tensioning of the cable structure – the so-called “Big Lift” – required all the experience of the PFEIFER installation specialists, the greatest possible care had to be exercised. In March 2009 the time had finally come:

All 72 axis had been connected with bolts and a temporary pre-tensioning system had adjusted the cable structure to its final geometry.

Construction of the roof could finally start. Nightshifts had to be introduced and all the work processes had to be interlocked due to the enormous pressure to meet deadlines. To prevent the installation from proceeding in fits and starts, teams were doubled and each individual team had to strictly adhere to its deadline, much like in line construction. Preparation and installation of the steel trusses, installation of the connecting girders, preparation and installation of the grid iron for the glass panes, installation of the glass – all that happened at the same time only a few meters apart, day and night 7 days a week. The PFEIFER-Team and the up to 500 workers on the site were stretched to the limit. By 6th August 2009 the roof structure was installed, all the cranes dismantled and the pitch could be handed over to the general contractor within the deadline.

3. Perspective

The responsible authorities expect the construction of the Cape Town Stadium on the inner-city “Cape Town Common“ and in immediate vicinity to other tourist attractions to further enhance and upgrade the neighborhood. Cape Town’s attractivity around the stadium is further increased by sports venues, a golf course and pedestrian zones between Waterfront and Beach Promenade. Development of the stadium into a multi-functional arena has begun; the roof in its role as the visual highlight and weather-protection element will contribute its due share to that.

With the reliable execution of the stadium roof project in Cape Town, PFEIFER has made a name for themselves also as general contractors for the construction of such special structures. Apart from the cable structure as their core competence, PFEIFER have gained a reputation by coordinating the efforts of all the trades working on the roof and have shown a high degree of competence in planning, delivery and installation.

4. Parties Involved in the Construction

Client: City of Cape Town, South Africa
General Contractor: Green Point Stadium Joint Venture Murray & Roberts / WBHO Joint Venture, Cape Town, South Africa
General Contractor Roof: Birdair/Pfeifer Joint Venture under the leadership of Pfeifer Seil- und Hebetechnik GmbH, Memmingen, Germany
Planning: gmp Architekten – von Gerkan, Marg und Partner, Hamburg, Germany with POINT ARCHITECTS, Cape Town, South Africa
Engineers: sbp gmbh Schlaich Bergermann & Partner, Stuttgart, Germany