Umm... well, I'm not exactly sure what to call this. I'm not even sure what the purpose is. But, I have seen things like this featured in many games where you can duck into them to escape from bad guys sight.
Anyway, this is one of thase industial floorholes. Rails are mid-high poly, some modifiers are still active, basic materials, rendered in cycles. More of a base mesh.
Enjoy.
very cool ;-)