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PASSIVE SAFE POLES - Even TRIGLASS® utility poles are considered passive safety elements

Crushing test utility poles triglass

Exaclty like lighting poles, even utility poles can become dangerous elements if cars crash into them. 

For this reason, Top Glass has decided to measure the passive safety of its own poles by analyzing the parameters described in the European standard EN 12767 in some crash tests at Transpolis S.A.S. 

PARAMETERS

The parameters analyzed on the different set-ups and perfectly described by the European standard regulation EN 12767 are:
  • the speed class of the vehicle during the crash test. A minimum speed of 35 km/h is the prerequisite for the maximum speed that can be of 50, 70 or 100 km/h. Top Glass chose the last one. 
  • the energy absorption categories, divided into “no absorption” (NE), “low absorption” (LE) and “high absorption” (HE) category.
  • the occupant safety class, from A (low gravity) to E (high gravity).
  • the collapse mode of the pole, that can determine a detachment from the foundation or a simple collapse (SE or NS).
  • the direction class of the vehicle.
  • the penetration of objects into the passenger compartment with the risk of a roof indentation.

TEST SET-UP

According to the EN 12767 standard, the set was composed of 3 utility poles 8 meters long and connected by elctrical cables to imitate a real installation. 
The vehicle used for the impact (Peugeot 106) weighed 910 kg and contained all the necessary equipment to direct the test, and control and record the speed of acceleration or deceleration. Inside, was collocated a SID to detect further data during the impact, such as the effects of the crash on the driver.

Two speeds were tested: a minimum speed of 35 km/h and a maximum speed chosen from 50, 70, and 100 km/h. Among them, Top Glass opted for the highest one.

TEST RESULTS

The impact at 35 km/h caused a slight rebound of the vehicle and the subsequent deformation of the pole: this is something natural according to what is described in the referring standard. The impact at 100 km/h caused a consistent fragmentation of the central pole that crashed to the ground without any detachment from the foundation. The cables on the top broke down but the vehicle wasn’t hit by them. 

Therefore, the results of the test showed that the utility poles of 8 meters of lengths are included in the "no energy absorption" category (NE) as the vehicle output speed was slightly reduced from 100 to 71 km/h.

The utility poles 8 meters long are the "progenitors" of a family of products that also encompasses poles of 7 meters of length. As a consequence, the crash test results obtained for the poles of 8 meters can certainly be considered valid for the immediately inferior length too: the 7 and 8 meters long ultility poles achieved the category of "no energy absorption" and the occupant safety class C level which is a great result on a range that goes from A (low severity) to E (high severity).
    Futher information about EN 12767/2019 standard


Passive safety of support structures for road equipment - Requirements and test methods

The EN 12767 European standard specifies the requirements and test methods to assess the Passive Safety of supporting 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 910 kg. The car is equipped 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 determines 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
  • MD=multi-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 intermediate sizes.

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