The red lines are the spaces where the people that build the walls might drill, it's that dense because behinde me in that picture there are 3 rooms with together 6 loops and in the middle left  behind the wall is the manifold 

They started on the far end and when they got to behind the camera, they realized how many lines they still had to run to that area and the amount of space in the hallway to feed that area didn't line up with the spec for the spacing in the room. Instead of ripping out what they had done, they just increased the density.

Same thing as when you're signing your name on a birthday card and the first few letters are huge, but the you've gotta shrink the rest to fit before you run out of paper.

I'd agree with you on it being a hallway. I'd also guess the red mark out is for a demising wall.

distribution maybe?

Every line in needs a line out. Looks like they lead toward the photographer.