That bridge looks more than a bit like the Sydney Harbour Bridge in Australia.

The Shorpy moment I have been waiting years for—I can see my apartment building in this photo. It's the building just left of the central church tower, behind the darker building behind a stack (which is the 1922 Julia Richman High School, still there).

Right behind the Waldorf is the original GE Building, an art deco masterpiece. Across the river is the old Astoria generating plant and on 72nd Street another old power plant.
Most of industrial NYC is gone now, having been torn down for high rise residential and office towers.

You were right to be warned of the whirlpools lurking beneath Hell Gate Bridge. There's a reason why the river is called Hell Gate at that spot. The East River itself is not actually a river but a tidal estuary, the water changing direction with the tide's ebb and flow. The currents at Hell Gate are especially dangerous for navigation because that point is getting the tide from two directions: Up the East River from New York Harbor and from Long Island Sound to the east.

It's possible to date this picture fairly precisely even though the caption just says "1930's." The New York Hospital was the last of the major buildings to be completed, in 1932, and as it took just a couple of years to build it's probably either nearly complete or already completed in this view.

Construction of the Triboro Bridge began in 1934.* Within a year the towers for the East River crossing in front of the Hell Gate Bridge were complete and the bridge opened in 1936. As there's no sign of the tower construction in this view, I'd say the photo was taken between 1932 and 1934.

Although there is a great deal of commuter rail traffic in New York, commuter trains don't use the Hell Gate Bridge. Amtrak and freight trains are its sole users.

* = the groundbreaking ceremony for the Triboro Bridge actually was in 1929, but no doubt because it happened *literally* the day after the Great Depression began, not much work happened for several years.

I was a kid in Astoria in the 40's. To the right of the bridge was Astoria Park, where we used the very large swimming pool in the Summer time. We were warned of the awful whirlpools which lurked beneath the bridge - probably just to scare us off from taking a swim in the East River. I believe that the gas storage tanks which were a part of the scenery in most large cities have all disappeared. This photo predates the Triboro bridge which would have been this side of the Hell's Gate Bridge.