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PASSIVE SAFE POLES - TRIGLASS® Lighting Poles successfully tested according to EN 12767/2019

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Lighting poles are one of the fixed obstacles on roads; official data show that the number of road accidents due to collisions with these elements exceeds 5000 cases each year.

TOP GLASS Industries S.p.A. is engaged in an activity of characterization of the crushing resistance for the different types of poles which produces. Initially, in 2021, the test relatively to the Utility poles with a length equal to 8 m were performed: the No Energy class was obtained.

After that, in July 2022 TOP GLASS have also made the crushing resistance test for all the TRIGLASS® Lighting Poles obtaining the Low Energy (LE) class for pole lengths from 11 to 12.6 m, and the No Energy (NE) class for the all the poles from 3m to 10 m.

This important certification allows TRIGLASS® Lighting Poles to be considered an important passive safety element that can be easily installed on urban roads and highways.

The “behavior” of the lighting poles during a collision largely influences the severity of the impact in terms of the damage caused to the people and vehicles involved.
“Behavior” means mainly the response that the pole has to impact and its capacity to absorb energy, and can be summarized in three categories:

  • Non-Energy Absorbing (NE): The pole is designed to detach or break in the event of impact, the car pass through the pole without losing too much speed 

  • Low Energy Absorbing (LE): The pole breaks due to the impact, and the car is slowed by the pole losing a lot of speed 

  • High Energy Absorbing (HE): The pole is deformed by the impact but remains embedded in the ground, the car is stopped by the pole (Fig. 1c)

The tests were performed by Transpolis S.A.S. Laboratory according to the EN 12767/2019 standard. This European standard 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.

LIGHTING POLE CHARACTERISTICS

The tests were performed on poles with a length of 11.6 m ad 9 m. According to the standard the first test is valid for poles with a length from 11.6 to 12.6 m, instead the second one for a pole length lower than 10 m. The results obtained can be considered representative for all these poles length produced by TOP GLASS Industries.

To simulate the worst application conditions, not only the pole was installed, but also a luminaire was fixed on the top with a metallic bracket of 100 cm and electrical cable connected. The weight of the bracket and the luminaire was about 10 kg.

The poles were installed on a backfill of sand and gravel with a controlled granulometry (GNT 0/31.5) to guarantee optimum compactness.

TEST SET-UP

The standard defines that the test can be performed at three speeds. TOP GLASS chosen to apply the highest one in order to verify the performance of the TRIGLASS® Lighting Poles in the worst conditions and with the speed recommended also for the application in rural roads and highways.

The tests were performed for “Class 100”, that includes a first test at 35 km/h and a second one at 100 km/h.

According to the standard, the vehicle used for the crushing test presented an inertial mass of 810 kg and was equipped with the instrumentation needed for control the test and recording the speed acceleration and deceleration of the vehicle and the effect on the driver. Moreover, a large series of photos and video was done to analyze the results and the damages generates on the poles and on the vehicle.

TEST RESULTS

The main result of the crushing tests performed on TRIGLASS® Lighting Poles showed that the pole with a length of 11.6 m have a “Low Energy” absortion category (LE), while the pole with a length of 9 m obtained a “No Energy” absorption category (NE).

The energy absorption is an important parameter that takes into account the exit speed of the car after the impact: the poles are considered NE if the car pass through the pole without losing too much speed; they are considered LE if the car is slowed by the pole, losing a lot of its speed. In the test performed at 100 km/h on the pole with length 9 m, the result showed an exit speed of 79 km/h, includes in the range for the NE class (between 70 and 100 km/h according to the standard). The longer pole presents an exit speed equal to 58 km/h, includes in the range for the LE class (between 50 and 70 km/h).

The main reason of this result difference in relation to the pole length is related to the geometrical properties of the poles, the glass fibre percentage and the poles mechanical properties. These poles are certificated CE according to the EN 40; TOP GLASS chosen to guarantee high mechanical properties for all its poles. For this reason, particularly for the longer poles, high glass fibre percentage, a diameter and wall thickness proportionally increased with the length were designed. These elements influenced the pole weight and inertia moment, and consequently the crushing test results.

Another important result is the occupant safety class, that for TRIGLASS® Lighting Poles results “C”.

This parameter includes the theoretical impact of the head against any point of the car and the deceleration that the passenger will endure. The class goes from A (very low severity) to E (most important severity); class C is considered a good results for structures as lighting poles with the length tested and subjected to the conditions previously described.

The collapse mode observed in the tests was “no separation”, that means a no complete break of the pole that undergoes an evident deformation. In Figure 3 and 4 the collapse at 35 km/h and 100 km/h respectively is showed.

    Futher information about EN 12767/2019 standard


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

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
  • 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 intermediates sizes.

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