Ok, I did search first, but only found posts finding the overhead lines, but in the CNT TV in game preview vid, when it cuts to the "underbelly" segment, you see a guy say "common guys" I think, in background is a two segment transport with overhead connections. TECHNICLY could be a electric bus system as well, but thought I would throw it out there. Link is:
http://crave.cnet.co.uk/gamesgear/new-gta-5-screenshots-and-videos-feast-your-eyes-50012159/
http://funsizedcomics.com/wp-content/uploads/2013/09/20130908-173756.jpg
Already posted, then sorry!