The Concrete Society’s TR34 Defined Movement (4th Edition) Classifications

The flatness classification that CoGri USA recommend is that contained within table 3.2 of the Concrete Society’s Technical Report No.34 (4^th Edition), in which section 3 discusses flatness requirements for very narrow aisle (VNA) warehouse floors, how to achieve them, the allowable values of the properties of flatness and how to measure them.

Table 3.2: Permissible limits on Properties dZ, dX, d²Z and d²X in defined-movement areas.

Floor Classification	Racking top beam height	Property Z_SLOPE	Property dZ	Property d²Z	Property dX	Property d²X
Calculation	–	mm per m	Z x Z_SLOPE	dZ x 0.75	Fixed values 2 x Z_SLOPE x 1.1	Fixed values
DM1	Over 13m	1.3	Z x 1.3	Z x 1.0	2.9	1.5
DM2	8 – 13m	2.0	Z x 2.0	Z x 1.5	4.4	2.0
DM3	Up to 8m	2.5	Z x 2.5	Z x 1.9	5.5	2.5

Properties Measured

The following properties are defined in Figures 3.8 – 3.10 as follows:

Property Z: The transverse dimension between the centers of the truck front wheels, in m.

Property X: The longitudinal dimension between the center of the front and rear truck axles. This is taken to be a fixed 2m.

Property Z_SLOPE: The cross-aisle slope between the centers of the truck front wheels in mm/m.

Property dZ: The elevational difference in mm between the centers of the truck front wheels.

Property dX: The elevational difference in mm between the center of the front axle and the center of the rear axle.

Permissable Limits

Table 3.2 details the allowable values of the properties of flatness for differing categories.

N.B The values shown for dX and d²X are based on a longitudinal dimension of 2000mm (this is a fixed dimension)

It is not possible to specify and impose these limits for defined movement unless the exact design of the VNA installation is known before construction. The choice of classification to specify is dependent upon the height of the top beam of the racking.

However, the recommendations of the VNA fork lift truck manufacturer should also be sought, as each model is designed to cater for different requirements and is therefore affected differently by surface regularity.