The above and below images accompanied a March 20, 1957 NY Times article discussing the proposal. According to the article 80 to 85 percent of the trolley’s riders were City employees either getting off or on the trolley at the mod point of the Queensboro Bridge to take the then elevator down to Welfare Island where they were employed at either Coler or Goldwater Hospitals. Under the proposal to switch to direct service, the trolley-goers were to be afforded door to door bus service to and from each hospital.
I am unsure if this is how the last trolley came to its end but I am guessing the full story can be found in the Queensboro Bridge Images of America book now being sold by the RI and Astoria Historical Societies.
On April 7, 1957, the last trolley, Car 602, rattled across the Queensboro Bridge, making one last stop mid point across the bridge at Welfare Island and proceeded across to Queens Plaza. According to the NY Times article of that day, riders were not afforded direct bus access prospectively to Welfare Island but were able to take the Q101 from Second Avenue in Manhattan to Queens Plaza, as you can still do stoday, and transfer to the Q102 onto Welfare Island.