A Little History

I'm gonna leave most of the history open, but for the sake of continuity, I'm going to have a couple details of the end of the world available:

1) This is an infection zombification, not voodoo or toxic sludge or any other such bullshit. It was spread by virus through bites or mucus membranes (tainted blood/spit/bodily fluids contacting open orifaces). This is most similar to 28 Days Later in this respect.

2) These are fast moving zombies. Slow moving zombies really only make sense as grave risers because they would be decomposing and their shit might fall apart. These are still living beings that contain the apparatus to run...so why wouldn't they?

3) The zombie horde must eat humans, it is the only food that they want and the only thing that can sustain them. They are not truly undead, this infection is closer to rabies, though much more violent, and seems as though it won't kill them as long as they can eat. Even though they don't seem human anymore, they still need to feed. As a corollary, it seems as though they don't excrete anything (needs more research).

4) These zombies have the same senses as humans. Thus they communicate through rudimentary sounds.

5) The virus cannot survive outside of a human body for more than a minute or two.

6) The city is almost constantly surrounded by zombies, though this sometimes thins out, presumably so they can hunt and feed.

7) The city's population is approximately 20% of what it was before the zombies. And the survivors have fallen back to a defensible position so there is much urban sprawl that used to be part of the city right outside of the barricades. Again, if anyone thinks of anything else, leave comments and if it sounds good I'll add it in here.