Shelton made to lay low, then heard, "Oh, thank god. Excuse me," and realized someone else was about to enter the bathroom. Hoping Kerzach could stall for him, Shelton slid the sheet metal out of the way and squeezed into the machine room, just ahead of the upcoming occupant. No time to put the sheet metal back.
The scientist poked his head into the machine room, curious. After a few seconds of not seeing much, he shrugged and his head disappered.
The second the head was gone, Shelton crawled out of the machine room corner, dropping the sheet metal he'd hid behind. Using the pipes to climb over the sight zone of the bathroom hole, Shelton reached the other end of the machine room.
Here there was an entrance to the main lab; the old secret elevator shaft, which had been cleared and sealed. A series of rungs led up to the top of the lab.
I wonder if I'd get radio reception up there, he thought. I could contact James and see who had been in the destroyed truck, or if I could help them out somehow.
Making sure not to look down (for the bottom of the elevator shaft was open to the road speeding below him), Shelton grabbed the rungs and started up to the roof of the lab.