5.1 Within the supply transport chain, there are a number of different stresses
acting on the cargo. These stresses may be grouped into mechanical and climatic
stresses. Mechanical stresses are forces acting on the cargo under specific
transport conditions. Climatic stresses are changes of climatic conditions including
extremely low or high temperatures.
5.2 During transport various forces will act on the cargo. The force acting on the
cargo is the mass of the cargo (m) which is measured in kg or ton, multiplied by the
acceleration (a) which is measured in m/s2 :
Acceleration considered during transport are the gravitational acceleration (a = g =
9.81 m/s2) and acceleration caused by typical transport conditions such
as by the braking or rapid change of traffic lanes by a road vehicle or by the
motions of a ship in heavy sea. These accelerations are expressed as product of the
gravitational acceleration (g) and a specific acceleration coefficient (c) e.g. a =
0.8 g.
5.3 The following tables provide the applicable acceleration coefficients for the
different modes of transport and for the various securing directions. To prevent a
cargo from movement, the cargo has to be secured in longitudinal and transverse
direction according to the worst combination of horizontal and corresponding
vertical accelerations. The securing arrangement has to be designed to withstand the
forces due to accelerations in each horizontal direction (longitudinal and
transverse) separately (see chapter 9 and annex 7).
| Road
transport
|
| Securing
in
|
Acceleration
coefficients
|
| Longitudinally
(cx)
|
Transversely (cy)
|
Minimum vertically down
(cz)
|
| forward
|
rearward
|
| Longitudinal direction
|
0.8
|
0.5
|
-
|
1.0
|
| Transverse direction
|
-
|
-
|
0.5
|
1.0
|
| Rail transport
(combined transport)
|
| Securing
in
|
Acceleration
coefficients
|
| Longitudinally
(cx)
|
Transversely (cy)
|
Minimum vertically down
(cz)
|
| forward
|
rearward
|
| Longitudinal direction
|
0.5 (1.0)†
|
0.5 (1.0)†
|
-
|
1.0 (0.7)†
|
| Transverse direction
|
-
|
-
|
0.5
|
1.0 (0.7)†
|
| † The values in
brackets apply to shock loads only with short impacts of 150
milliseconds or shorter, and may be used, for example, for the
design of packaging.
|
| Sea
transport
|
| Significant wave height in sea area
|
Securing in
|
Acceleration
coefficients
|
| Longitudinally (cx)
|
Transversely (cy)
|
Minimum vertically down (cz)
|
| A
|
Hs ≤ 8 m
|
Longitudinal direction
|
0.3
|
-
|
0.5
|
| Transverse direction
|
-
|
0.5
|
1.0
|
| B
|
8 m < Hs ≤ 12
m
|
Longitudinal direction
|
0.3
|
-
|
0.3
|
| Transverse direction
|
-
|
0.7
|
1.0
|
| C
|
Hs > 12 m
|
Longitudinal direction
|
0.4
|
-
|
0.2
|
| Transverse direction
|
-
|
0.8
|
1.0
|
5.4 The effect of short term impact or vibrations should always be considered.
Therefore, whenever the cargo cannot be secured by blocking, lashing is required to
prevent the cargo from being significantly displaced, taking into account the
characteristics of the cargo and the mode of transport. The mass of the cargo alone,
even when combined with a high friction coefficient (see appendix 2 to annex 7),
does not sufficiently secure the cargo as the cargo can move due to vibrations.
5.5 The significant 20-years return wave height (Hs) is the average of the
highest one-third of waves (measured from trough to crest) that is only exceeded
once in 20 years. The allocation of geographic sea areas to the respective
significant wave heights is shown in the following table:
| A
|
B
|
C
|
| Hs ≤ 8 m
|
8 m < Hs ≤ 12 m
|
Hs > 12 m
|
| Baltic Sea (incl. Kattegat)
Mediterranean Sea
Black Sea
Red Sea
Persian Gulf
Coastal or
inter-island voyages in following areas:
Central Atlantic
Ocean (between 30°N and 35°S)
Central Indian Ocean (down
to 35°S)
Central Pacific Ocean (between 30°N and 35°S)
|
North Sea
Skagerak
English Channel
Sea of Japan
Sea of Okhotsk
Coastal or inter-island voyages in
following areas:
South-Central Atlantic Ocean (between
35°S and 40°S)
South-Central Indian Ocean (between 35°S
and 40°S)
South-Central Pacific Ocean (between 35°S and
45°S)
|
unrestricted
|
Sources:
The Royal Netherlands Meteorological Institute (KNMI):
The KNMI/ERA-40 Wave Atlas, derived from 45 years of ECMWF reanalysis data (ed.
S.Caires, A.Stern, G.Komen and V.Swail), last updated 2011, Hs 100-yr return values,
1958 – 2000
5.6 During longer voyages, climatic conditions (temperature, humidity) are likely to
vary considerably. These may affect the internal conditions in a CTU which may give
rise to condensation on cargo or internal surfaces (see annex 3).
5.7 Whenever a specific cargo might be damaged when exposed to high or low
temperatures during transport, the use of a CTU specially equipped for keeping the
cargo temperature within acceptable limits should be considered (see chapter 7).