"I can remember street cars with overhead lines in Washington in the 50s so we’ve come full circle!"
I rode the trolleys in DC during the '50's. I remember the underground 3rd rail on most of the tracks. On the line out to Glen Echo the trolley had to stop so the driver could walk around back, unhook the overhead boom and guide it up so the shoe would engage the overhead cable. I can't remember if there were overhead wires inside the District line. Do you remember?
It’s my recollection that the overhead wires were only outside the District, and as you said, the driver would have to stop, walk around, and engage the overhead cable when he reached the end of the 3rd rail.
And another thing I remember - going up an incline when on the overhead cable - some rowdy teenagers reached out the back window and pulled the boom down, disengaging it, and received a stern warning from the driver. :-)