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A Dramatic Icon Towers Above New Racetrack
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Observation tower at the Circuit of the Americas racetrack in Austin, Texas
The observation tower at the Circuit of the Americas racetrack in Austin, Texas, was designed and built with fast track measures, shaving three months from the schedule. © Paul Finkel/Piston Design

The new observation deck at the Circuit of the Americas racetrack in Austin, Texas, affords spectators unprecedented views of the action below.

May 28, 2013—The dazzling red and white observation tower rising 251 ft tall above the Circuit of the Americas racetrack in Austin, Texas, was designed to evoke the dynamism of the Formula 1 race cars that howl past it at speeds approaching 220 miles per hour. The tower, like the cars, was built with a lightweight, efficient structure as the construction team raced to the finish line—the inaugural U.S. Grand Prix on November 18, 2012.

The tower’s defining feature is a series of bright red, high-strength steel 8 in. diameter tubes that cascade from the top of the structure down the front of the tower and above a contiguous amphitheater. These tubes, known as the veil, provide both lateral load resistance for the tower and serve as the top chord for the rigging canopy above the amphitheater stage. The project was designed by Miró Rivera Architects (MRA), the Austin firm, led by Juan Miró, FAIA, LEED AP and Miguel Rivera, AIA, LEED AP. (Utilities design and grading around the tower was conducted by Carlson, Brigance, & Doering, Inc., of Austin, which also conducted the civil engineering for the racetrack itself; read their First Person feature article on the project published in the May 2013 issue of Civil Engineering here.) 

Another view of the observation tower

The tower serves as an icon that helps visitors find their way
around the expansive site. Courtesy of Circuit of the Americas

“The first concept that Juan and Miguel had was the flat horizon. When you see the road going off into the horizon, you get this narrowing of the perspective,” says Ken Jones, RA, LEED AP, a senior associate at MRA. “On top of that, you think of great time-lapsed photography of cars winding around the path. You see the trailing lights. The two combine to create that distinctive form of the veil as it comes up and over the top of the observation deck.”

The architects wanted the tower to serve several key functions at the 3.427 mi track. With a large observation platform 230 ft above the undulating track, the tower provides unprecedented views of the racing action. The tower’s height also makes it an easily found marker of the central plaza, the entry point for about half of the track’s visitors.

“Because it occupies the multiple functions of wayfinding, icon, and observation tower that is unique to Formula 1 racetracks, it was so important, and we wanted to make sure we signified that through this dynamic structure,” Jones says. “It is very dramatic and that is not by accident.”

The team had developed the concept and schematic level designs from the beginning, but it wasn’t green lighted for construction until late 2011, less than 12 months from the inaugural race.

Observation tower featuring is a series of bright red steel tubes that cascade from the top of the structure down

The tower’s key design feature is a series of bright red steel tubes
that cascade from the top of the structure down, providing lateral
load resistance for the structure. © Miró Rivera Architects

“We very quickly put together enough documentation to go through permitting—which was really no small feat for either the permitting authority or us,” Jones remembers. “There is nothing really in code that speaks to this type of structure. When you start building a platform 230 ft in the air, there are not a lot of code precedents for that.”

Once it became clear that permitting the tower was possible, the team turned to how to build it. Structural engineers from the Austin office of Walter P Moore were brought in very early in the process. Together they developed an innovative diagrid system in which two exterior staircases are arranged in a double helix around the tower. The stair treads and risers are welded together, enabling the stairs to function as a diaphragm. Immediately outside of the stair stringers is a layer of diagonally-oriented hollow structural steel (HSS) 3x3 members; stacked outside of these diagonals is a layer of vertical HSS 4x4 columns, according to an MRA fact sheet on the project.

“Rather than building this massive structure that would support the height of the observation deck, it was extremely important to us that the structure for the tower be as light as possible,” Jones says. “The only way to make that happen was to have everything be functional.”  

The attention to detail paid off—the tower uses just 380 tons of steel. Atop the tower, a 896 sq ft viewing deck cantilevers out, supported by the diagrid tower members. A portion of the deck is made of structural laminated glass and it is surrounded by a glass guardrail system. The deck has a capacity of 75 people. In addition to the stairs, the tower has a 27-person-capacity elevator that can travel 450 ft per minute.

The team had approximately one year from the green light phone call to the race date. That meant—appropriately enough—that they would have to fast-track the Formula 1 tower project. Engineers built a full model of the tower in building information modeling (BIM) software developed by Tekla, headquartered in Finland.

View of the observation tower, looking upward

The observation tower stands 230 ft high, affording spectacular
views of the entire track. A portion of the deck is made from
structural laminated glass. © Paul Finkel/Piston Design

“We didn’t have time for a typical delivery schedule where we do design documents, and then it goes out to a fabricator and his detailer, and he goes through procurement and detailing, and then it comes back, and the design team reviews it, and sends it back,” Jones explains. Instead, the fabrication shop prepared drawings directly from the BIM model.

At the site, the team had to contend the expansive clay soils that are prevalent in east Austin—the same soils that challenged Carlson, Brigance, & Doering on the track, where crews removed as much as 10 ft of soil and replaced it with 940,000 cubic yards of select fill. For the tower, crews removed 9 ft of soil and replaced it with compacted fill. The tower is founded on a structural slab, supported by a series of 36 in. diameter piles that extend 45 ft to higher-quality material.

The team selected Patriot Erectors of Dripping Springs, Texas, to build the tower, and brought them on early to work through the erection process. Large sections of the structure were shipped to the site and assembled into 25 ft tall segments that were then lifted into place by cranes.

Jones says the BIM models and fast-tracking procedures eliminated approximately three months from the potential construction schedule. “When you consider we finished five days before the race, that’s an awfully good thing,” he adds with a laugh.

The team didn’t have a long rest, however. The project also included the Austin360 Amphitheater, a 6,761-seat venue that was added late in the design stages. Although the tower was complete for the race, much of the amphitheater work was scheduled after the race to minimize the impact on spectators.

“As soon as that race was over, we started the actual erection of the rigging canopy,” Jones says. “We are able to use those pipes from the veil structurally as a top chord, and we use the rigging grid as the bottom chord for that spanning member. We get to do something that is beautiful, yet functional, at the same time.”

The amphitheater is nestled into the infield topography of the plaza, which includes a reflecting pool, concession stands, retail areas, and restrooms. It is the largest outdoor venue in central Texas, building on Austin’s reputation as the “Live Music Capital of the World.”

Approximately 117,000 spectators attended the inaugural race, which was a financial boon to the area. The City of Austin estimates the race garnered the city $191 million in free media exposure and that area hotels took in $32 million during the event. In addition to the Formula 1 race, the facility will also host races in the MotoGP, V8 Supercar, and American LeMans series.

The tower has been well received by the track’s developer and the inaugural race’s spectators, Jones says. It has become an attraction in its own right at the $300-million, 375-acre facility, visitors flocking to see the expansive views—and has also become the new “photo-op” landmark of Austin, Jones says.


 

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