I'm making a left 4 dead map in forge and if you have ever played left 4 dead you would know that to pass a certain level, you have to go into a safe room. (For those who don't know, an area where zombies can't get you and a place that transitions you into the next level.) Now it just occurred to me that when you have an infection map you can't make an area to start a new round. Meaning like if you were making an obstacle course in halo 3 you would use something like a oddball to pick up and end the round to start a new one. The only idea I have with my infection map is to get to the safe room before times runs out and without dying. Have any other ideas?
Have you tried experimenting with safe havens? With a little tailoring I'm sure you can make it work for you.
I'd suggest looking at! Act 1 & 2 The Sewers and The Streets. I forgot who made them, but that may be your answer on how to end it. I haven't really played them so it may be different than what you are looking for. Hope it helps!