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Glass corridor in Bronx Zoo puts public nose to nose with gorillas, safely

Laminated glass is strong yet "soft", clear and safe – for gorillas and humans.

At the heart of the New York Bronx Zoo Congo Gorilla Forest Exhibit a corridor winds its way down a "jungle" hill, allowing the general public and the 270 kg gorillas to safely view each other very closely – sometimes nose to nose – with only 5 cm of laminated glass separating them.

SAFE – WITH UNINTERRUPTED VIEWS

Project architect at Helpern Architects, Jeff Rosenberg, told LGN: "The primary design goal we shared with the Wildlife Conservation Society's Exhibition and Graphic Arts Department was that visitors should feel that they are actually in the African Congo. The laminated glass walkway is butt-jointed with no mullions for ultimate optical clarity and gives the appearance of having been fabricated in one piece. The result is 180-degree, uninterrupted views."

"We selected laminated glass for its strength; through research with other zoos, we had learned that an angry gorilla can charge its cage at up to 24 km/h! After extensive calculations with our structural engineering team, Mahler Architectural Consultants, we concluded that the safety of both the public and the gorillas would be best assured with laminated glass. The result is spectacular!"

STRONG YET 'SOFT'

Floral Glass of New York supplied the laminated glass for the project. Company president Chuck Kaplanek told LGN: "The glass units were designed for strength and security. Three lites of 12mm heat tempered glass are laminated together with two triple-thickness interlayers of PVB. The result is three or four times stronger than bullet-resistant glass. The panes are made in a variety of curved, trapezoidal shapes, allowing the glass corridor to following the jungle hill upwards." "However, the glazing solution also had to be 'soft' – the zoo did not want to risk either the animals or the public getting hurt. Luckily, this has always been a feature of laminated glass since the first laminated glass automotive windshields, 60 years ago. While being 'soft', the glass is thick enough not to deflect in the event of massive impact - especially important since the large panes of floor-to-ceiling glazing also provide the structural strength of the construction."