The European standard EN 12 767 specifies the requirements and test methods to assess the Passive Safety of support structures for Road equipment.
Passive Safety is intended to reduce the severity of injury to vehicle occupants in case of impact with road equipment.
In this standard, any kind of road equipment can be assessed, but the most common are the sign support, signal support, lighting column, utility pole, cantilever support.
The following description explain the test set-up and procedure, the possible test results and the classification of the poles.
Evaluation by crash-test
The object of this standard is an impact test of a vehicle with specific characteristics against a pole. Whatever the category, the car to be crash-tested is a standard passenger car of 900 kg. The car is instrumented with plenty of sensors and data measurements box, so that severity criteria may be measured. The crash-test is filmed with high-speed cameras.
The main criteria which define a pole are:
- Speed class
- Energy Absorbing category
- Occupant safety class
- Collapse mode behaviour
- Direction class
- Risk of roof indentation.
A test is non successful if the severity criteria on occupants are too high or if a part of the pole penetrates inside the vehicle.
a. Speed class of a pole
The standard defines 3 Speed Class: class 50, class 70, class 100.
It’s upon to the manufacturer to choose the class he wants its pole to be compliant with.
For each class selected, the pole need to be crash-tested at 2 different speeds:
- At the speed of the class ( 50, 70 or 100 km/h)
- At a lower speed: 35km/h.
A speed class of 50 will be preferred for poles to be installed in city, whereas a class of 70 or 100 can be preferred when poles are installed on rural roads, highways, etc.
b. Energy Absorption Category
The Energy Absorption of a pole is a very important parameter which determined a lot of other parameters.
Three categories exist, defined by the exit speed of the car after having impacted the pole:
- HE = High Energy Absorbing: the car is stopped or almost stopped by the pole.
- LE = Low Energy Absorbing: the car is slowed by the pole, losing a lot of its speed
- NE = Non-Energy Absorbing: the car pass through the pole, without losing too much speed.
The following table shows the correspondence between the energy absorption category and the speed class:
c. Occupant Safety Class
The occupant Safety class goes from A (very low severity) to E (most important severity) and is defined by 2 values:
- THIV: it corresponds to the theoretical impact of the head against any point of the car
- ASI: it corresponds to the deceleration that the passenger will endure.
THIV and ASI values need to respect specific value in order the pole to be classified into one of the category A,B,C,D,E. If one of the values is too high, the pole cannot be compliant to the EN 12 767 standards.
Generally, A and B are for plastic delineator or similar harmless device; C category generally applies for NE pole; D and E for LE and HE.
d. Collapse Mode
Two collapse modes can be observed:
- SE = Separation Mode. The pole breaks / separates.
- NS = No separation Collapse Mode. The pole didn’t break, it mainly deforms and wraps into the car.
NB: for a same pole, we can observe the two different collapse mode: It is often bound to the test speed.
e. Direction class
The poles can be categorized into three Direction Class:
- SD = single-directional
- BD= Bi-directional
In a general manner, a pole having more than two symmetric axes is considered as a MD: the exact location of the vehicle impact into the pole doesn’t matter, the pole will have its same performance and can be installed in a cross section, in median strip., etc.
A pole that doesn’t have two symmetric axes, will have to be tested successfully at different angle to get the MD classification.
f. Risk of roof indentation
This criterion gives a classification about roof deformation due to the pole falling in the vehicle
Class 0: roof deformation < 102mm
Class 1: roof deformation >102 mm
Notion of Product Family
The standard introduces an important focus on product family. If a pole is manufactured in different sizes, not all the sizes need to be tested:
- The tests need to be run on the biggest/higher pole.
- Given result obtained on the higher poles, additional tests need to be done on the smallest pole.
- According to the result on the smallest pole, additional test may be necessary on intermediates sizes.