Cockrell School alumnus Mark Waggoner, M.S. CAEE '99 and engineer with Walter P Moore, offers a first-hand perspective on his involvement designing the structures at the Circuit of the Americas Formula 1 track, most notably the towering 250-foot tall observation tower with its distinctive red racing stripe veil.
On Sunday, Oct. 21, Mario Andretti expertly piloted a Lotus 79 Cosworth around the 20 turns comprising the Circuit of the Americas (COTA), the newly constructed racetrack that will host the inaugural Formula 1 United States Grand Prix in Austin this month. Normally, events such as the "First Lap Ceremony" are reserved for dignitaries and celebrities, but a timely tour gave members of the COTA design team the chance to glimpse the swift first racers on a track facility they had spent months designing. These designs will be put to the test when COTA welcomes 12 race teams and more than 120,000 visitors from across the globe for the first race.
My firm, Walter P Moore, designed the structures for more than a dozen buildings, bridges and other objects that make up the facilities at COTA. With a long history of providing structural engineering for iconic sports and events structures dating back to the Astrodome, we were honored to be selected to help design the latest generation of world-class sports facilities in Texas. The team in our Austin office, led by myself, and in Dallas, led by David Platten, P.E. (M.S.E. UT Austin, '80), collaborated with architects from Miró Rivera Architects (MRA) in Austin, HKS in Dallas and Tilke GmbH from Germany on the project. With an extensive staff of graduates from The University of Texas at Austin's prestigious structural engineering program in the Cockrell School's Department of Civil, Architectural and Environmental Engineering, 10 engineers with UT Austin degrees contributed to Walter P Moore's design efforts at COTA.
While the pit row and grandstands at COTA provide a familiar setting to other racetracks around the world, Mr. Andretti could be forgiven if during his first lap he lost concentration coming around turn 16 when the observation structure came into view. A 250-foot tall steel lattice diagrid tower shrouded in a distinctive red racing stripe veil, the observation structure was conceived by MRA as the single point where the entire racetrack can be viewed at once. Spectators can ride the elevator from the base, or take the stairs to the observation level, which offers distinctive views as well as a glass floor for viewing the track below.
When Juan Miró, a professor at the university's School of Architecture, first approached us with the concept for the observation structure, he proposed a tower built from extremely slender three- and four-inch square steel shapes. Though contrary to conventional solutions for this scale of structure, Miró's concept piqued a fit of curiosity in our team, and we pressed on to find a solution. Often ignored as a structural element, the stairs themselves proved to be key to the design. Working with MRA we arranged the two flights of stairs in a double helix fashion, similar to DNA, around the elevator shaft and connected key points with a network of slender columns and braces to form what is known as a diagrid tube structure. Every portion of the tower - down to the treads of the stairs - contributes to the ability of the structure to carry the weight of occupants and the effects of strong winds on the track site.
Other structural challenges were present throughout the COTA site. Cursed with some of the most expansive clay soils in the Central Texas region, a variety of elaborate foundation strategies were deployed to enable cost-effective construction of the buildings. The grandstand is a unique modular steel structure that was designed to be expanded in the future. A translucent tensile membrane canopy over the grandstand seating combined with open concourses — shaped to generate breezes — provides for passive spectator comfort without requiring expensive mechanical systems. The bridge structures we designed to cross the track include a precast concrete girder bridge span that is only a foot shy of the state record (we tried, but the track configuration dictated the span).
The sort of designs we were challenged to produce at COTA must be built from a fundamental understanding of structural behavior. Just as Mr. Andretti expertly navigated the challenging curves of the COTA track that Sunday, the education my UT colleagues and I received has enabled us to find innovative paths to guide our way through the twists and turns of designing one-of-a-kind structures.
