Part-2 The Physics of a Giant: Engineering the 150-Meter Clear Span
Behind the monumental presence of the Indira Gandhi Indoor Stadium lies an engineering narrative that serves as a profound lesson in physics.
In an era before the luxury of modern design software like STAAD, Tekla, or ETABS, the engineering team of Shashi Prabhu, Hadkar Prabhu & Associates—led by the late Mr. N. B. Hadkar and Mr. Kamal Hadkar, faced the daunting task of designing a 150-meter diameter clear-span roof. Without a single internal column to support the weight, the team relied on manual mechanical calculators, logarithmic tables, and slide rules to perform thousands of complex structural iterations.
Entrance photo of Indra Gandhi Indoor Stadium Circa1980
To anchor this massive canopy, they utilized Slip-Form Shuttering to rapidly cast eight enormous pylons, each rising 12 stories high. These pylons were not merely aesthetic bookends; they served as the load-bearing backbone of the entire structure, designed to anchor the staggering 4,000-tonne steel roof.
Tiered Seating arrangement at the Indra Gandhi Indoor Stadium Circa1980
To manage the unprecedented physics of the span, the team employed the concept of the "Structural Bicycle Wheel." The roof was engineered to behave like a colossal horizontal wheel, utilizing a massive concrete compression ring as the "rim" and an inner tension ring as the "hub." Steel girders extended outward like structural spokes, tying the system together into a self-supporting unit.
Ceiling of Indra Gandhi Indoor Stadium Circa1980
However, the size of the roof created a secondary challenge: Delhi’s dramatic temperature swings, which fluctuated between 1° and 45°. To prevent this movement from fracturing the concrete support, the engineers implemented "Thermal Floating." The steel roof was engineered to sit over Polytetrafluoroethylene (Teflon) bearings, allowing it to expand and contract freely above the pylons, safeguarding the structure from long-term fatigue and cracking.
External View of Indira Gandhi Indoor Stadium, Delhi in 1982
In sports architecture, precision is paramount because every dimension carries a consequence. The 4,000 sqm arena was shaped with an almost obsessive focus on the "C-value"—a mathematical calculation of sightlines. Through a carefully graduated cross-section of tiers, each of the 25,000 spectators was guaranteed an unobstructed view.
Banks of Yamuna River grazing the stadium site
The engineering also had to account for the environment; built on the Yamuna riverbed following the devastating floods of 1978, the structure was strategically elevated with strengthened embankments. Even the pouring of concrete was a battle against the climate. As Ar. Shashi Prabhu recalls, the winter cold meant concrete wouldn't set properly, requiring the use of heaters and protective blankets to ensure structural integrity.
Today, 43 years later, the stadium remains the largest indoor sports arena in India—a living icon of what can be achieved when mathematical discipline meets unwavering ambition.
Author: Amol Prabhu, Sweta Singh