Well, let's look at the clues. First, the third rail puts it on the Electric Division east of Croton or North White Plains. If it's on the Hudson, the camera is pointed east (south) because the transmission line (steel lattice towers on the right) was on the river side between Croton and Spuyten Duyvil. It is an interlocking, from the three-arm home signal. But IIRC, none of the Hudson Electric interlockings between DV and CD had home signals on single masts like that one - they were on signal bridges. So, let's try the Harlem.
There is an overhead bridge in the background. It's not North White Plains or Mott Haven, so the other possibilities are JO at Woodlawn (looking west from west of the New Haven flyover bridge), BG at Botanical Garden, VO at Mount Vernon or RK at Crestwood.
The third rail has wood sheathing, and the signal has the smaller backgrounds, so it is probably NYC after 1955 or so, when they changed over to the smaller signal backgrounds.
I'm not well enough qualified on the Harlem to make the distinction, but if I had to bet the farm I would say Crestwood. I'll stare at it some more and maybe another light bulb will come on over my head.