Franklin Metro utility is a metro utility tunnels and part of the metro network. It's slightly irradiated, heavily so in some places, and partially water-filled. The metro track tunnels are a section of the Blue Line east of Franklin Station, which has exits to Falls Church and Hubris Comics.
With Broken Steel installed and the Lone Wanderer's level being higher than 20, many ghouls will be replaced with feral ghoul reaver. At the extreme end, every single ghoul, bar one or two roamers, will either be glowing ones or feral ghoul reavers, and due to their proximity, one may be attacked by a group as large as five at once, particularly in the heavily irradiated tunnel.