I'd be shaking in my Red Wings if I were one of those guys. No way I'd want to be walking around in a tunnel where 3 ton chunks of ceiling have already fallen and there's still some up there. I do notice they seem to be sticking toward the parts with no panels or small panels, wearing a hard hat in those circumstances is kind of a twisted joke.
Yeeeeaaah... I sure as hell wouldn't walk through there.