Updated 6/15/2020:
While work continues on the scenery in the Ohio River valley and on the bridge, some electrical work has also been conducted ("nyuk, nyuk, nyuk").
Awhile ago, I acquired a second 12V DC power supply. Today I re-arranged some of the other supplies and mounted them all vertically so as to get more air flowing around them. I also decided that I will move 3VDC "wall warts" to remote power strips located at the ends of the layout. These will power street lights (my lighted telephone poles) and traffic signals. Here's the new transformer cart diagram. Changes were made primarily to the lower level of the cart.
Here's a shot of the work (in progress). Left to right - the new 12VDC supply, the existing 12VDC supply, and the 5VDC supply. The barrel connector to the extreme left is the 3VDC supply which is yet to be moved.
More when I know it. 
George
