Definition
The Triborough Bridge Authority (TBA, later the Triborough Bridge and Tunnel Authority, TBTA, after the 1946 absorption of the New York City Tunnel Authority) was a public corporation chartered by New York State in 1933 to complete construction of the Triborough Bridge — a three-bridge complex connecting Manhattan, the Bronx, and Queens via Randall's Island.
Robert Moses became chairman in 1934 and remained chairman until 1968, when the Authority was absorbed into the Metropolitan Commuter Transportation Authority (now the MTA). During his 34-year tenure Moses used the Authority as the structural instrument of his power, expanding its mandate from a single bridge to a regional monopoly on toll bridges and tunnels.
What Triborough actually was
The expansion
Triborough's mission expansion across 34 years illustrates how flexible the public-authority form is in practice:
1933-1936. Build the Triborough Bridge. The Authority's original and bounded mission.
1937-1945. Build additional bridges (Marine Parkway 1937, Bronx-Whitestone 1939, Henry Hudson 1936). The covenants permitted application of surplus to related projects; new bridges qualified.
1946. Absorb the New York City Tunnel Authority. Triborough now controlled every toll crossing in NYC.
1946-1968. Expand into parkway construction, parks, slum clearance, and ultimately the 1964 World's Fair. Each expansion was justified as related to Triborough's existing mandate; the bond covenants permitted the expansion; no elected official could legally block it.
By 1960 Triborough had grown from a single-bridge agency into the structural center of New York City public works — a transformation that the original 1933 legislation had not contemplated.
The structural innovations Moses encoded
The Triborough enabling legislation and bond covenants — both drafted by Moses or under his close direction — contained several innovations that became templates for subsequent American public authorities:
The related-project clause. Surplus revenue could be applied to projects related to the Authority's existing function. The definition was deliberately broad. Modern public authorities routinely include similar language.
The refinancing power. The Authority could refinance its own bonds with new covenants, restarting the contractual clock indefinitely. Moses refinanced strategically through the 1940s and 1950s, extending Triborough's contractual sovereignty into the 1990s.
The for-cause removal standard. The chairman could be removed only for cause, with cause subject to litigation. Moses could not be fired the way a city commissioner could be fired.
The board composition. The Board was specified in the enabling legislation in ways favorable to the chairman, and the chairman appointed key staff.
Triborough today
The Authority continues to exist as the Triborough Bridge and Tunnel Authority, a subsidiary of the MTA. It operates the same nine crossings Moses oversaw, plus the Verrazzano-Narrows Bridge (opened 1964). Toll revenue continues to subsidize NYC's transit system — a use Moses opposed and that the post-1968 absorption made possible.