The new Silver Line is called that because it will be one of the fastest bus transit systems, and silver is a color often associated with speed (ie: silver bullet).
here are the lyrics:
H is for my alma mater Harvard,(It's a parody of the children's song "Mother" and is sung to the same tune:
C is Central, next stop on the line,
K is for the cozy Kendall station, and
C is Charles that overlooks the brine.
P is Park Street, uh, Pahk Street, busy Boston center
and W is Washington you see...
Put them all together, they spell:
HCCKKCC... PW... (spitting sound)
Which is just about what Boston means to me
"M" is for the million things she gave me, "O" means only that she's growing old, "T" is for the tears she shed to save me, "H" is for her heart of purest gold; "E" is for her eyes, with love-light shining, "R" means right, and right she'll always be, Put them all together, they spell "MOTHER," A word that means the world to me. Howard Johnson (c. 1915)
...the Green Line isn't the only line to use letters to designate its different branches. The A, B, and C branches of the Red Line are the Ashmont, Braintree, and Alewife branches, respectively....streetcars still run on the T. Take the Red Line to Ashmont, and hop on the Ashmont-Mattapan High-Speed Line. It uses old streetcars from the Green Line. If you look at the destination indicator inside some of the cards, you'll see that it still says "Park Street" and other such green line destinations.
...the M.T.A. took pride in the speed of the Green Line. All over the line were posted signs that said " __ Minutes to Park Street". The last of these signs exists at Lechmere, just over the Passenger viaduct, where it said "12 Minutes to Park Street".