In reply to JOH.

I haven't seen the comp lab floors at your university, but having seen the U.S. in comparison to here, the floors, if not mopped and swept would be absolutely covered in mud, hunks and clods and too slippery to walk on, brought in from all the places that have no paving whatsoever. To reduce the effort the school has to put into the sweeping and mopping, they have a concrete paved entrance ramp that help the kids get most of the mud off their shoes before entering the building. :)