On the flat and narrow!

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Floor flatness has a significant impact on efficiency and safety when materials are handled by forklift trucks. Although the Concrete Society’s Technical Report TR34, published in 1988, was a pioneering step and contains the principal standards used to determine floor flatness in warehouses, construction methods and operators’ demands have left it behind in some important respects.

Back in the 1980s, when the original survey investigation work was carried out as the basis for the new floor flatness standards, most floors – particularly those for narrow aisle operations – were constructed using the long strip method. This method of construction virtually always produced very good longitudinal characteristics, in respect of both short wave length and long wave length.

Occasionally a floor would fail in the transverse direction, but only marginally. Presumably, because the original working party found so few problems with longitudinal flatness, the original standard covered this aspect in a fairly cursory fashion. The weakness of TR34 in this respect has been highlighted by the replacement of the traditional long strip method of construction with laser screeding, followed by grinding to achieve a reasonably flat finished surface.

However, as the standard only applied to the transverse measurement and the short wave-length characteristics of the outer two wheel tracks, warehouse operators and truck manufacturers often found the trucks could not be operated as specified, particularly as they were increasingly expected to lift higher and travel faster.

In addition, with many very narrow aisle (VNA) trucks now incorporating sophisticated computer systems and even being guided down the aisle by low frequency cables in the floor, the standards of floor flatness actually achieved has become increasingly important.

It was against this background that the Concrete Society set up a special working group in 2001 to consider the issue of floor flatness in defined movement areas such as warehouse aisles. The results of this working group’s deliberations are new standards which include for the first time measurement of the positions of all wheels and a long wave-length control. The new standards came out in March and, although they cannot be enforced, they are accepted in general by all the industries concerned.

Appendix C of the new edition of TR34 includes maximum values for differences in levels laterally and longitudinally for all wheel tracks within defined movement areas and also stipulates the rates at which levels change. Values are specified for three fork truck lift heights – up to 8m, 8m to 13m, and more than 13m.

The new specification is based on a similar set of standards that has been in use in the US since the late 1970s, and has been introduced as the basis for a possible future European FEM (Fédération Européenne de la Manutention) standard.

The third edition of TR34 also proposes a new method for surveying defined movement areas, using a profileograph that simulates the dimensions of the trucks to be used. The profileograph survey produces a continuous profile of the floor surface in relation to the specification as it travels along the wheel paths of the lift truck, effectively recording the regularity of the floor as a truck would experience it.

The new TR34 edition closes a significant loophole in the standards relating to floor flatness. Warehouse owners and operators should now be able to get the standard of flatness they require for safe, efficient operation of lift trucks without any ambiguity. n

Kevin Dare is managing director of FACE Consultants, and a member of the Concrete Society working group on floor regularity, tel: 01484 600080.

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