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Visitors to London during the 2012 Summer Olympics had a unique perspective atop the Dome.
Now that the dust has settled on the London Olympics, the story can be told about how ordinary people were able to walk up the fabric roof of the O2 Dome (formerly Millennium Dome), and survive the winds and weather to walk down the other side on a custom fabric walkway.
Designed by Rogers Stirk Harbour + Partners with Buro Happold—the same team that designed the original dome—the roof walk, called “Up at the O2,” is a combination of architecture, engineering and extreme visitor experience. The climbing facility starts on the south side of the O2 where a staircase with glass enclosed elevator brings people up 7.5m to a staging platform and the beginning of a tensioned fabric walkway that is suspended above the dome roof. Climbers ascend the 30° incline curving roof with a lanyard cable and handrail the entire walkway. Climbers are issued a climb suit and harness that they attach to the cable that guides them as they move toward the top, 50m above ground, where a 12m diameter viewing platform (with spectacular 360° views of London) awaits them. A return walkway leads climbers back down to ground level on the north side.
Considering that none of the walkway and access structures were allowed to touch or compromise the structural integrity of the original dome, it becomes obvious that design, engineering and fabrication magic was performed here. Up at the O2 is a partnership between AEG and O2. Appointed to oversee construction and deliver the project in time for the 2012 Summer Olympics was main contractor ISG. ISG hired Base Structures Ltd. to design the connections, and fabricate and install the cable tensioned walkway and central viewing platform at the dome’s apex.
The technical challenges the project presented were considerable. “The first problem to overcome,” says Mark Smith, director and head of projects with Base Structures, “was to ensure it was actually physically possible to walk up the fabric surface [of the dome].” With the steep, 30° slopes of the dome, Base’s testing of various fabric surfaces proved that a custom material was needed for the design concept to succeed. From a construction standpoint, there was the additional problem that no existing crane could reach far enough to fully access the work site. Base Structures solved many of the problems by breaking the project down into manageable bits and with lots of prototype testing in the shop. Proven methods were applied to sections of the walkway, preassembled in the shop, then transported to the site and fastened into place, a strategy that worked well given England’s notorious weather. With April 2012 on record as the wettest ever, Base was forced to do most of the installation work on weekends to meet its deadline.
Fabric manufacturer Mehler Texnologies contributed to the project by creating a custom PVC fabric with a non-standard textured surface to increase traction. After much testing, a modified design emerged that incorporated thick ribbing applied across the width of the walkway fabric for the entire length of the walk. The ribbing acts like pliable ridges that offer climbers additional grip between shoe treads and inclined walkway.
The ultimate solution to the numerous challenges is a successful combination of cable suspension fabric bridges that hang from the massive yellow truss masts that hold up the dome.