For the 4.4-million-square-foot Terminal 2 at Chhatrapati Shivaji International Airport, in Mumbai, India, Skidmore, Owings & Merrill designed a moment-resisting steel-truss frame that is softened by thousands of precision-made glass-fiber- reinforced concrete panels and gypsum panels.

For the 4.4-million-square-foot Terminal 2 at Chhatrapati Shivaji International Airport, in Mumbai, India, Skidmore, Owings & Merrill designed a moment-resisting steel-truss frame that is softened by thousands of precision-made glass-fiber- reinforced concrete panels and gypsum panels.

Credit: Robert Polidori

The grid of columns and ceiling coffers at the Chhatrapati Shivaji International Airport Terminal 2 in Mumbai, India, recalls the intricately carved stone mandapas, or pavilions, of ancient Hindu temples. But everything else about this 4.4-million-square-foot transportation hub, designed by Skidmore, Owings & Merrill (SOM) to serve 40 million travelers per year, is thoroughly modern.

Thirty massive concrete-encased steel columns structurally bear the terminal’s 1,150-foot-by-900-foot roof, with 111- and 210-foot clear spans between supports. The columns also create a powerful aesthetic that helped fulfill the client’s goal for more than just a sleek international airport. “They wanted it to feel like it belonged in India,” says Roger Duffy, FAIA, the project’s design partner. For design inspiration, he met with historians, studied traditional choreography, visited archeological sites, and collaborated with Indian designers Abu Jani and Sandeep Khosla.

Upon learning that the peacock, India’s national bird, is a symbol of life, Duffy and his colleagues chose the iridescent, teardrop-shaped eye of the tailfeather as the inspiration and motif for the molded coffered panels that clad the terminal’s ceiling and columns.

The airports arrivals and departures area offers passengers shelter from rain, particularly during India's monsoon season. Though Formglas made the FRP molds for the exterior panels, a Chinese company fabricated the GFRC panels. Two 400-millimeter-diameter roof drains run down each exterior and interior column behind the panels.

The airport’s arrivals and departures area offers passengers shelter from rain, particularly during India's monsoon season. Though Formglas made the FRP molds for the exterior panels, a Chinese company fabricated the GFRC panels. Two 400-millimeter-diameter roof drains run down each exterior and interior column behind the panels.

Credit: Robert Polidori

The 131-foot-tall columns rise the full height of the terminal, passing through openings in each of the four floors, and culminating with a 111-foot-wide capital that mushrooms into the 17-acre ceiling. To design the coffered panels, Duffy says the SOM team “essentially made a 3D map of the ceiling [and capitals], and then segmented it into a taxonomy of pieces.” Each piece is a molded coffered panel measuring approximately 9 feet 2 inches by 8 feet 9 inches; panels at the capital are slightly smaller. With their teardrop shapes, all panels reflect the peacock eye motif. The interior panels are molded glass-fiber reinforced gypsum (GFRG) while their exterior counterparts, in areas such as the arrivals forecourt, are made from glass-fiber reinforced concrete (GFRC) to withstand weather.

The airports long-span steel structure is supported by a grid of composite mega-columns that comprise a 2.3-meter-square cruciform steel structure encased in a 2.7-meter-diameter concrete casing. The panels attach to the structure with a system of aircraft wire and steel hooks molded into the glass-fiber-reinforced gypsum and concrete.

The airport’s long-span steel structure is supported by a grid of composite mega-columns that comprise a 2.3-meter-square cruciform steel structure encased in a 2.7-meter-diameter concrete casing. The panels attach to the structure with a system of aircraft wire and steel hooks molded into the glass-fiber-reinforced gypsum and concrete.

Credit: Robert Polidori

To meet the tremendous scope and scale of the panels, the designers partnered with Formglas Products, a Toronto-based molded architectural products company. Formglas brought SOM’s digital models into the 3D CAD software CATIA to make the molds. “That allowed us to detail everything [including overlaps and joints] to nth degree,” says Formglas senior vice president Richard Samson.

Five-axis CNC machines cut each shape from molded medium-density fiberboard (MDF). Formglas then layered fiber-reinforced plastic (FRP) over those shapes and took a “negative,” which became the mold. In all, Formglas’s manufacturing plants in Toronto and Mexicali, Mexico, built more than 500 different molds and produced more than 15,500 different components for the roof, capitals, and columns.

What makes the design special, Duffy says, is the precision with which each panel was fabricated. “You can barely see the joints, making the columns and ceiling look as if they were carved from a single piece of stone,” he says. To produce such a fine surface, Samson explains, each FRP mold was thoroughly sanded and buffed. “The quality of the panels is only as good as the quality of the surface of the molds.”

At the center of each of the 8,500 coffered panels is a 2- to 3-foot-diameter aperture for natural and electric light to pass. In each aperture is a laminated lens with a disc of dichroic film that produces two colors, depending on the angle at which light strikes it. SOM positioned the film to create a geometric pattern of color on the ceiling itself and the floor below. “When the light is right, the whole airport looks like a Rajasthan palace filled with colored glass,” Duffy says.


  • What makes the design special, SOM's Roger Duffy, FAIA, says, is the precision with which each panel was fabricated. You can barely see the joints, making the columns and ceiling look as if they were carved from a single piece of stone, he says. The peacock-eye-shaped ceiling panels continue down fan-shaped column capitals. Dimpled diamond panels cover the column shafts.

    Credit: Robert Polidori

    What makes the design special, SOM's Roger Duffy, FAIA, says, is the precision with which each panel was fabricated. “You can barely see the joints, making the columns and ceiling look as if they were carved from a single piece of stone,” he says. The peacock-eye-shaped ceiling panels continue down fan-shaped column capitals. Dimpled diamond panels cover the column shafts.

Roof trusses running at 45 degrees to the orthogonal grid were added to provide additional stability and diaphragm stiffness, allowing for 40-meter cantilevers around the perimeter with a truss depth of only 4 meters.

Roof trusses running at 45 degrees to the orthogonal grid were added to provide additional stability and diaphragm stiffness, allowing for 40-meter cantilevers around the perimeter with a truss depth of only 4 meters.

Credit: Robert Polidori