I recently saw several Verizon trucks in my area up and down the street for about 5 to 6 blocks. The Verizon Techs were lowering a white tape like "cable" of a spindle into each manhole. Then Con-Edison trucks the next few days.
Closeup view of the black fiber cable with connector
We just got VZ Fios installed in our house, and the black fiber cable is very similar to the RG-6 coaxial cable in size, it's a bit flatter (not as round) - if you are up close enough to touch & look, you can see the white lettering identifying it as fiber.