The situation in free movement areas is very different from that in defined movement areas. Because there is an infinite number of possible traffic paths in a free movement area it is impossible to specify and survey them all. So representative sampling of flatness and levelness is the only choice. Some assumptions have to be made to ensure that the sample survey is representative of the whole area.
No specification for control of flatness and levelness of free movement areas can be perfect. Because of the practical limitations on the number of level points and survey lines which can be assessed, there will always be a possibility that some point on the floor surface is out of tolerance but is not detected. The best approach is to choose a specification that gives a reasonable assessment of surface regularity and which is easily applied and checked by survey.