This is a portal mod I'm working on. Donald Otter is apparently friends with Cave Johnson , and Cave has given Donald permission to copy Aperture Science products.(This is coming out of my imagination, not Valve's). You are a test subject at Otter Research Facility. I am not yet going to make a mod page, as I only have one map done ATM.
I added this grate to show how cheap and uncreative Donald Otter is.
Normally a path to a hazardous testing course would be on a different level, not through a grate of a parking area.