It can be seen that flatness is generally related to variations over shorter distances whereas levelness is generally related to longer distances. These distances are not easily definable, but traditionally flatness has been controlled over a distance of 600mm and levelness over a distance of 3m. Where mhe is operated in defined-movement areas, floor surfaces are measured over distances relative to the dimentions of the mhe.
The methods of assessing surface regularity described below assume the floor is to be horizontal and not laid to falls.
Departure from datum - The deviation in height of the surface of all new floor construction should be within +/- 15mm of the mean floor level.
Free and defined-movement - In warehouses, mhe is used in two distinct areas of traffic movement:
- In free movement (FM) areas, mhe can travel randomly in any direction. Free-movement areas typically occur in warehouses with wide aisle racking installations, factories, retail outlets, low-level storage, marshalling zones and food distribution.
- In defined-movement (DM) area, vehicles use fixed paths. Defined-movement areas are usually associated with high level storage racking with verry narrow aisles (VNA) in warehouses.
Distribution and warehouse facilities often combine areas of free-movement for low-level activities such as unloading and packing alongside areas of defined-movement for high level storage.
Different surface regularity specifications are required for each floor use so that approapriate performance of the floor can be achieved. The different specifications are reflected in the survey techniques used and the limits on measurements (proprieties) that are prescribed.
Where racking layouts have not been determined at the time of construction, the developer is advised to build to as high a standard as possible: a free movement surface regularity category FM2 is suggested. This will limit the amount of grinding required in aisles to meet defined-movement tolerances if VNA is subsequently installed.