Creating a tall, slender air traffic control tower – without a damper
Standing 84m tall, about the height of a 30-storey building, the Air Traffic Control (ATC) Tower in Mumbai’s international airport gives its staff unobstructed views of their entire operating environment.
ATC towers tend to be both tall and slender; these characteristics make the structures vulnerable to wind-induced movement. Left unchecked, this movement would make the towers uncomfortable for their occupants: ATC professionals doing critical work.
To mitigate wind-induced movement, most of the world’s ATC towers rely on specially designed damping systems. The designers of the Mumbai airport’s ATC tower wanted to create a tower that didn’t require such a system. Knowing they needed to find another strategy to address the risk of uncomfortable motion, they envisioned a distinctive form at the base of the tower that would break up the formation of vortices and thus diminish wind effects on the tower’s upper floors. The design team turned to us for help optimizing the geometry of their design in order to maximize the structure’s safety and comfort.
Our wind engineering team embraced the opportunity to work with the tower’s architects (HOK) and structural engineers (Arup) to achieve their innovative vision. We collaborated closely with the designers to understand the environment the tower would operate in, and to gain insight into their unusual strategy for mitigating wind effects.
We developed a detailed scale model of the structure, including the distinctive skirt design at its base, and subjected the model to extensive testing in our wind tunnel. After modeling and quantifying the wind-induced vibrations the tall structure would experience in a range of weather conditions, we were able to offer precise recommendations on how to optimize the shape and orientation of the skirt at the tower’s base to maximize its ability to mitigate wind effects and maximize occupant comfort.
The design of the skirt structure was refined and tested iteratively. Ultimately, we were able to demonstrate that the final proposed design would effectively disrupt vortex shedding and keep the tower’s peak accelerations within acceptable limits for office occupancy, even in the absence of a supplemental damping system.
The tower has been operating successfully since 2013 and has been celebrated for both its architectural and technical sophistication. It is equipped to handle both current and future air traffic control needs, in a market where air travel is growing at approximately 10% per annum. During the design process, the tower won the Autodesk Hong Kong Building Information Modeling Award (2009). Upon completion, it was recognized by the Indian Concrete Institute as an Outstanding Concrete Structure (2013).