The seal of the Triborough Bridge and Tunnel Authority appears on a large plaque on Battery Place at the mouth of the Brooklyn-Battery, or Hugh Carey, Tunnel. I do not know when the seal was designed, but it appears to depict the Bronx-Whitestone Bridge. Also included is wrought metalwork depicting tunnels beneath waves suggesting water.
The owl is a universal symbol symbolizing intelligence and wisdom, while the beaver symbolizes industriousness; the beaver can also be considered a symbol of NYC, since early Dutch traders trafficked in beaver pelts. Even after the colonial era, John Jacob Astor made his massive fortune in such trade, and ceramic beavers were placed in the subway station uptown named for Astor Place.
The Triborough Bridge and Tunnel Authority has been around since 1946 and administers all tolled bridges and tunnels in, and connecting to, New York City. It was formed in 1940 when several disparate agencies, controlling several different structures, merged into one. NYC traffic czar Robert Moses was its chairman for the first couple of decades of its existence. In addition to bridges and tunnels, the Authority also constructed the Brooklyn Battery Parking Garage and the now-razed New York Coliseum.
In 1968, the TBTA became an agency of the NY Metropolitan Transit Authority. Subsequently, moneys collected via tolls have contributed to the upkeep of NYC’s transit network: subways, buses, Long Island Rail Road and Metro North Railroad. Officially the agency is now called MTA Bridges and Tunnels.