The Verrazano Narrows Bridge Othmar Ammann’s Greatest Work of Structural Art
THESIS In designing the Verrazano Narrows Bridge, Othmar Ammann created his greatest work of structural art, combining elegance and simplicity over a huge span, with important social and symbolic roles.
SCIENTIFIC ASPECTS • Steel cable suspension bridge • Length: 4260 ft. • Height: 690 ft. • Deck thickness ratio: 1/180 • Simple stiffening deck truss
Caisson construction used to build towers • Each leg of tower stands on 33 foot concrete pier, which remains low profile • Towers designed slightly further apart at the top than at the bottom, due to the curvature of the earth • Towers exhibit simple, clean design • Only one cross-pieces at the top of the towers, no ambiguity
Massive concrete-housed cable anchorages on either side of bridge -Not only connect the cables to the ground, but are used to store and heat salt and cinders for icy conditions.
SOCIAL ASPECTS Three S’s: Social • 12-lane, two level bridge (huge traffic volume) • Large trucking route connecting NJ to Long Island • Provides more efficient travel route through New York City • Facilitated development of Staten Island • Increased business growth and in Brooklyn • Created a vast number of new jobs on either side, effectively starting a Verrazano Bridge industry
SYMBOLIC ASPECTS • Longest bridge in North America • Same impact on Staten Island as Brooklyn Bridge had on Brooklyn • Exceptional slenderness for its length while still appearing monumental • Frames entrance to New York Harbor • Opening of bridge celebrated with parades, parties, and an opening ceremony with thousands in attendance
Comparison with Golden Gate • Towers exhibit architectural quantities, ambiguous load path due to the four lateral elements • Original deck of Golden Gate not stiff enough, lateral bracing had to be added later, and the top deck had to be replaced altogether
Comparison to George Washington Bridge, also by Ammann • GW seems bulkier, not sleek • Originally designed for stone cladding, current design seems either incomplete, or too busy • Original deck also not stiff enough: present trusswork added later • Verrazano nearly twice as long, while considerably more slender and better at resisting forces