1.4.1  Horizontal and vertical shock loads

This type of load occurs primarily when switching freight cars and is taken to be 4 g for normal switching operations and 1 g for intermodal transport in the Guidelines for Packing of Cargo Transport Units, for example (see Table 1).

This places the packaging containers and packaged goods under considerable stress. If boxes are stacked, static friction between the boxes can cause shear stress on the bottommost boxes if there are gaps to the sides. The same applies with respect to the securing of the packaged goods.

Vertical shock loads can occur during handling, for instance if the packages are set down too hard. These are generally brief shocks that are not critical for the packaging itself, because the time the forces are acting is so short, but which can nevertheless damage highly-sensitive packaged goods. In cases such as this, shock-absorbing elements must, for instance, be used to secure the goods inside the packages.

1.4.2  Tipping loads / risk of tipping

Horizontal acceleration may also cause packages to tip.

A package is at risk of tipping if the area of contact with the floor is small and the center of gravity is high after due consideration of the acceleration to be expected. This is the case, for instance, if the center of gravity is above half the height of the package.

To determine whether packages are at risk of tipping, the ratio between the height of the center of gravity and the distance to the tilting edge must be determined. The tilting edge is always the edge perpendicular to the direction of acceleration (see Figure 2).

FG = weight force FV = acceleration force hs = tipping moment arm bs = resting moment arm

Figure 2: Checking the risk of tipping

Whenever the ratio of the height of the center of gravity over the base to the lateral distance between the tilting edge and the center of gravity is larger than the expected acceleration forces, the box is at risk of tipping and must be secured accordingly. Expressed in terms of ratios, this means:

to the front if	bs / hs < 1.0*
to the side if	bs / hs < 0.5*
to the rear if	bs / hs < 0.5*

* Example acceleration values during transportation by truck
  (CTU Packing Guidelines, see Table 1 in section 1.3.1).

1.4.3  Marking the center of gravity

In order to ensure that boxes can be handled safely, the position of the center of gravity must be indicated by an appropriate symbol on boxes as of 1,000 kg gross weight.

The center of gravity has been unambiguously indicated if the symbol is present on at least two adjoining walls of the box. To guarantee safety during handling and transportation, it makes sense to mark the center of gravity on all four side walls. The center of gravity is to be indicated in accordance with DIN EN ISO 780 or in accordance with the regulations of the destination country, see chapter 11.

1.4.4  Loads caused by oscillations/vibrations

Loads arising from oscillation and vibration occur during every transport. On the one hand, these result in vertical acceleration forces (see static loads), and, on the other, such vibrations can damage the packaged goods. Vibration-damping elements must be incorporated in the case of sensitive goods. As far as load securing is concerned, vertical oscillations reduce the friction between the loading surface and the package.

1.4.5  Loads during handling

Direct load values for handling general cargo are not available. Measurements carried out as part of a research project by the BAM (German Federal Institute for Materials Research and Testing, Berlin and the BFSV)* provide guideline values for acceleration loads applicable to the handling equipment used during container transportation, and these guideline values provide good coverage of the accelerations in the relevant directives/recommendations such as the VDI Directive 2700 and the Guidelines for Packing of Cargo Transport Units.

* Load values when handling containers and flats (BAM / BFSV)

Operation	max. acceleration [g] Container floor
Pulling away/stopping	0.3
Cornering	0.3
Lifting/setting down	3.7 (vertical) *

Operation	max. acceleration [g] Container floor
Lifting/setting down	4.8 (vertical) *
Lowering into ship	3.2 (vertical) *
Swiveling with change in height	0.4 (vertical) 0.2 (horizontal)

* see section 1.4.1

These load values should initially also be applied to the handling of general cargo.