EN 12195-1, the standard for securing the cargo according to the Directive 2014/47/EU
The EN 12195-1 standard, calculation of securing forces, constitutes the core of the Directive 2014/47/EU, as well as the main tool for sizing the cargo securing.
The standard contains the formulas to calculate the securing necessary to avoid the movement and the fall of the cargo during all phases of transport, including any emergency maneuvers. The formulas contained in the standard, based on the fundamental principles of statics of rigid bodies, allow for an analytical evaluation. This approach allows you to add analytical assessment to assessments based solely on common sense and experience.
The parameters needed to calculate the securing include:
- the cargo mass
- the arrangement of the cargo in the transport unit
- the acceleration coefficients during acceleration, braking and cornering
- the specifications of the securing equipment used. In case of use of web lashings reference is made to the UN 12195-2 standard
- the friction factor
Based on the principle that in any circumstance that may occur during transport the resultant of the forces and moments acting on the load must be zero, the formulas contained in the EN 12195-1 standard allow to calculate the minimum number of web lashings required for securing the load, or allow to calculate the required blocking capacity for a structural element of the vehicle, for example the front wall in the event of braking.
Once again, the analytical approach introduced by Directive 2014/47/EU is reaffirmed, which constitutes a real revolution with respect to the principle adopted up to now, which provided for a qualitative evaluation of the cargo securing, perhaps relying only on experience.
The EN 12195-1 standard provides for three securing methods:
Lashing: securing method where bending devices, such web lashings, steel wire ropes or chains, are used in the securing of the load on a load carrier. It is a securing method that uses only the traction force of the tensioning device. The two main types of lashings that can be used are frictional lashing method and direct lashing method.
Blocking: securing method where the displacement of the load is prevented by the direct action of a structural element of the transport unit, such as a wall or a side wall, or by external elements such as poles or blocking bars. Each blocking element acts in only one direction and sense.
Locking: securing method where the load is secured by mechanical devices on a load carrier. Each constraint, consisting for example of a “Twist Lock” coupling, carries out its action in all directions and senses.
For more information on securing methods, see the Cargo securing page
What happens to the cargo during transport?
Often there is a tendency to underestimate the magnitude of the forces that develop on the load during transport and which, if not adequately opposed by the securing devices or the transport unit structure, cause the load to move.
Another misleading aspect is related to the load mass: we would think that a very heavy load, for example a block of marble, is in itself “stable and well secured” thanks to its mass. Nothing more wrong! The inertia forces that develop while the vehicle is running are in fact directly proportional to the load mass. Therefore, even a heavy load, if not properly secured, could move forward in the event of sudden braking, or slip sideways when cornering.
Below is a brief description of the forces that develop on the load during transport, and which form the basis for the calculation of the cargo securing.
During transport, when accelerating, braking, cornering, or crossing holes and disconnections, inertia forces develop and tend to move the load or stress the structural elements of the vehicle, for example the walls.
In fact, it is noted that:
- When braking, the load tends to move forward
- During acceleration, the load tends to move backwards
- When cornering, the load tends to move towards the outside of the curve
- If holes or disconnections are encountered, or in maritime transport in case of rapid descent of the wave when there is rough sea, the vertical contact force between the load and the surface of the transport unit tends to be reduced
Le norme che regolamentano il fissaggio del carico introducono i coefficienti di accelerazione per tenere conto delle sollecitazioni (forze d’inerzia) che si sviluppano durante il trasporto, in modo da consentire il calcolo del fissaggio del carico.
The standards governing the securing of the cargo introduce acceleration coefficients to take into account the stresses (inertia forces) that develop during transport, in order to allow the calculation of the cargo securing required for a safe transport.
For road transport, the EN 12195-1: 2010 standard provides for the following acceleration coefficients related to the gravitational acceleration, g = 9.81 m / s2:
- 0,8g longitudinally forward, when braking
- 0,5g longitudinally rearward, during acceleration
- 0,5g transversely, when cornering (the coefficient must be assumed 0,6g in case of tilting for unstable goods)
It is clear that, for road transport, the most severe condition is represented by braking. In the case of rail or sea transport, the standard provides for different values for the acceleration coefficients, which take into account the stresses that develop in these modes.
Therefore, on a load with a mass equal to 1000 kg, could be actuated the following inertia forces during transport (values expressed in Newton):
- 1000 x 9,81 x 0,8 = 7848 N when braking
- 1000 x 9,81 x 0,5 = 4905 N during acceleration
- 1000 x 9,81 x 0,5 = 4905 N when cornering
These forces must be adequately balanced by the cargo securing system adopted, for example by the web lashings or the blocking bars used. Alternatively, these forces must be opposed by the transport unit structure if designed for that purpose.
The role of friction
Friction, always present to some extent, contributes to the securing of the cargo during transport by developing a frictional force Fa equal to:
Fa = μmg
μ: friction factor. The value depends on the combination of materials in the contact surface, for example Il valore dipende dal tipo di contatto, ad esempio wood-wood or wood-steel
m = load mass
g: gravitational acceleration equal to 9,81 m/s2
However, often the frictional force alone is not sufficient to secure the load, as shown in the following example.
Load mass: m = 1000 kg
Friction factor: μ = 0,3
Acceleration coefficient (braking): cx = 0,8
When braking on the load the following inertia force is actuated:
Fi = mgcx = 7848 N,
The inertia force Fi tends to slide the load towards the front of the transport unit.
Due to the load’s own weight and the friction factor, the following friction force is developed:
Fa = μmg = 2943 N
The force Fa tends to counteract the sliding of the load caused by the inertia force Fi.
However, the action of the friction force Fa alone is not sufficient to prevent the load from sliding, as a residual force equal to Fr = Fi – Fa = 4905 N remains.
The securing force Fr can be obtained by lashing, for example by using web lashings, chains or steel wire ropes, or by blocking, for example by leaning the load against the front wall of the vehicle. In this second case, it must be checked that the wall is designed for this purpose and offers sufficient blocking capacity, as in the case of vehicles approved according to EN 12642.
In both cases, the calculation of the securing can be carried out using the formulas contained in the EN 12195-1 standard, as shown in the dedicated pages in the Cargo securing section.