Beyond world records and athletic prowess, the Olympic Games have long been known for the massive urban overhaul and construction projects that host cities undertake to prepare for the onslaught of visitors. With instant architectural icons such as the Bird’s Nest and the Water Cube, the 2008 Summer Games in Beijing are a hard act to follow. When the International Olympic Committee (IOC) selected London to host the 2012 Games, many wondered how the city could top the design and engineering feats of its predecessor.
During its bid, London, like all of the short-listed cities, had pulled out all the stops, including proposals for extravagant new buildings. As the London Organising Committee of Olympic and Paralympic Games (LOCOG) and the Olympic Delivery Authority (ODA)—the joint organizations tasked with bringing the event to fruition—refined plans for capital development, the city’s pledge to the IOC to create “the first sustainable Olympic and Paralympic Games” would become the vehicle by which the new structures would make their mark.
The ODA, which is overseeing the construction of new venues and infrastructure for the Games, created the “London 2012 Sustainability Plan” that challenged architects to deliver facilities that would embody the spirit of the Games, create a lasting social, economic, and environmental legacy for the United Kingdom, and inspire change in the way that future events worldwide would be planned and built—all without compromising design. It established design targets for projects that included the use of environmentally friendly and ethically produced materials and the reuse or recycling of 90 percent of construction waste. “We encouraged designers to achieve a high quality of finish while adapting to this sustainability criteria,” explains Simon Wright, the ODA’s director for venues and infrastructure. “It provided quite a bit of a challenge, but in general, the designers were very creative in their solutions.”
The Stratford region of East London known as the Lower Lea Valley became the stage for a collection of world-class sporting venues that rely on structural ingenuity in a different way than their cousins of four years ago—to push the boundaries of not only what can be built, but also what can be built sustainably and for the long term. Spurred by ODA, the architects sought to design large-scale venues that minimize the use of materials and their footprints, both physical and carbon.
As the host for the central activities of the Games—the opening and closing ceremonies as well as the track and field competitions—the Olympic Stadium is the largest new venue to be built. Looking to the post-Games life of the building, the ODA determined little need for a facility with a capacity of 80,000 seats; London already has a number of large stadiums, such as Wembley and Emirates. So when the ODA handed its brief to the London office of Populous, which worked with structural engineer Buro Happold, it asked for a structure that could handily be downsized to 25,000 seats after the Games. “That transformation of going from 80,000 to 25,000 seats had never been done before,” says Philip Johnson, Populous’s project leader. “We had to figure out how to do it in a cost-effective and sustainable way.”
Material availability further complicated matters. Steel—the go-to structural material for a building that would be largely dismantled—was in short supply when the project was commissioned. After some research, Populous pinpointed a solution that would reduce the amount of steel typically required for a stadium of this magnitude by 75 percent: sink all 25,000 permanent seats and the lower bowl of the stadium into the ground. As a result, the earth, bolstered by some 5,000 reinforced concrete piles driven as deep as 20 meters into the ground, became the structural substrate for the permanent grandstand.
A lightweight steel structure comprising 112 rakers supports the 55,000 temporary seats in an upper tier around the excavated bowl. The design specified standard off-the-shelf, wide-flange structural steel sections, which workers could bolt together easily and, after the Games, dismantle and return to the market just as easily. These structural members were painted black to create a calming space through which visitors will pass before stepping into the excitement of the events inside the stadium.
The contrasting white steel members of the stadium represent an independent structural system that supports the venue’s 450-metric-ton (496-ton) cable-net roof system. The roof system covers two-thirds of the spectator seating with a 25,500-square-meter (274,480-square-foot) canopy of white PVC fabric. The canopy is supported by 3-inch-diameter steel cables drawn tight between an outer steel compression truss and an inner steel tension ring to create a rigid structure. The outer compression truss—composed of 28 steel sections each measuring 15 meters high by 30 meters long—transfers the entire weight of the roof system to concrete footings on grade through diagonal steel columns around the stadium’s 860-meter (2,822-foot) perimeter.
The steel used in London’s Olympic Stadium was sourced in a sustainable manner. The subcontractor obtained many of the tubular members that make up the roof structure from unused steel sections intended for a Russian oil pipeline. Workers cut and butt-welded the pipe sections together to form the truss ring, tension ring, and diagonal columns. “They are a little bigger in diameter than we wanted, but they worked,” says Johnson.
When completed, the elliptical-shaped stadium covered a 40-acre footprint with just 10,000 metric tons (11,023 tons) of structural steel—by far the lightest Olympic Stadium ever built. In comparison, the 91,000-seat Beijing National Stadium (the Bird’s Nest) for the 2008 Summer Games covered a 64-acre footprint and used 100,000 metric tons (110,231 tons).
While the Olympic Stadium may be considered the heart of the Games, the Aquatics Centre is the gateway to Olympic Park; the ODA expects more than two-thirds of visitors to enter the park on a bridge that spans a portion of the venue. London-based Zaha Hadid Architects wanted to devise a formally expressive roof structure to invoke the excitement of athletic competition and, in particular, the events within the Centre: diving, swimming, synchronized swimming, and the aquatics portion of the modern pentathlon. The challenge was to deliver an evocative profile with a non-obtrusive structural system.
The facility had to provide 17,500 seats during the Games, the second-highest capacity Olympic Park venue after the Olympic Stadium, and then drop to 2,500 seats, becoming the smallest-capacity venue for legacy use post-Games. The design team also had to create a facility in which, when filled to capacity, few if any structural supports would impede view lines.