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Overview of road safety barriers: how do they differ?

Safety Tips
September 2, 2023 9 min to read

Are you discovering the devices that make up the road safety world? Road barriers, crash cushions, and end terminals. If you work in the world of road barriers or you simply are a curious person, you are at the right place: in this article you will find a brief guide on the different types, also from a regulatory point of view, discovering the importance of their utility and how they can save lives.

What they are and what they are used for

A road safety barrier is a vehicle restraint system installed to contain and redirect any vehicle along the roadway. In other words, if the driver, losing control of the vehicle, leaves the roadway going against the obstacle, the barrier saves his life, stopping the vehicle or taking it back to the road.
Crash barriers world is various. It is estimated that there are hundreds of barrier manufacturers globally.

Types of barriers

Road safety barriers are mainly distinguished by the scope of application, type of installation, and type of materials.
Depending on the application, the distinction is between longitudinal barriers and frontal barriers. The most common longitudinal barriers are made of steel or concrete and they are classified as:

  • guardrails;
  • bridge parapets;
  • concrete barriers;
  • opening/removable barriers;
  • temporary barriers.

Frontal barriers are divided into crash cushions and end terminals.
In this article, we focus only on longitudinal barriers. They are distinguished as follows depending on the type of material used:

  • metal barriers (galvanized steel, steel with corten treatment, and some aluminum);
  • wood barriers;
  • prefabricated concrete barriers;
  • plastic road barriers;
  • on-site-built walls (although they should be considered as an alternative);
  • temporary steel and concrete barriers.

But, you may be wondering, what distinguishes one road barrier from another? The structure.

Metal barriers usually consist of a rail (double beam or triple beam) attached to a post. In general, when installing a barrier with rail and posts in the central reserve it can be applied as a double-sided barrier, consisting of one post plus the rail attached on both sides, and a single-sided barrier placed on both sides, consisting of the post plus the rail on the left side and the same on the right side.

Another difference is between permanent barriers driven into the ground (also known as “guardrails”) where the ground can be either soil or asphalt and permanent bridge rails (or bridge parapets), anchored on the reinforced concrete curb.

IMAGE 1 – CURB
IMAGE 2 – SOIL

Road safety regulation

Road safety regulation is not unique. In Europe, the EN 1317 standard is applied while in countries such as United States, Canada, Australia, and others the compliance with MASH-16 standard is required.
In this article we only focus on EN1317 compliant products.

Road safety regulation requires certified products to confirm the performance of the restraint systems following the crash tests, evaluate how the devices react to impact classify them according to specific performance criteria.
In particular, EN 1317 part 2 defines performance classes, impact test acceptance criteria, and test methods for safety barriers.

Compliance with the standard stipulates the issue of the CE mark that applies only to permanent longitudinal barriers.

Safety barriers are classified on the following basis:

  • Containment level;
  • Working width;
  • Dynamic deflection.

EN 1317 norm indicates containment classes, which are:

  • T (Temporary): 1, 2, 3 (lowest containment level);
  • N (Normal): 1, 2 (containment level indicated for the implementation of road barriers in cities, provinces, and municipalities)
  • H (High): 1, 2, 3, 4a, 4b (highest level of containment)
IMAGE 3 – CONTAINMENT LEVEL

An additional safety barrier classification, in addition to containment levels, is the working width.

 

The working width (Wm) is the maximum lateral distance between any part of the barrier on the undeformed traffic side and the maximum dynamic position of any part of the barrier. (Cfr: EN 1317-2).

 

The working width allows us to determine the geometric conditions for the choice of the type of device to be installed.

IMAGE 4 – WORKING WIDTH

The maximum transverse dynamic displacement of the containment system front (the displacement of the road barrier following the impact of the vehicle) represents the dynamic deflection (Dm) and it is fundamental to evaluate the useful workspace for the correct operation.

As for containment levels, also the working width consists of different levels.

The working width result is expressed through “W” followed by a number. For example, “1” represents the best score, as the distance of the barrier from the starting point following the impact is less than or equal to 60 cm.

IMAGE 5 – DYNAMIC DEFLACTION

This element is fundamental when it is necessary to evaluate the installation space on the roadside and especially for median.

Containment level and working width depend on the need to contain vehicles and especially, in the last years, heavy vehicles.

How to choose a road safety barrier

Choosing the road safety barriers to be preferred, we must keep in mind a series of aspects such as:

  • The type of road on which to install the device;
  • The speed limit of the road;
  • The roadway space.

The first point concerns the average traffic on a specific road section. In this case, it is necessary to evaluate a type of barrier with an adequate level of containment in both urban areas and highways.

If we think that not all drivers respect the required speed limits, there is a necessity to build road barriers with efficient and durable performances.

When you have to choose the “best” barrier, be aware to consider both working width and dynamic deflection.

When you have to choose a bridge rail or a median barrier (and then you must evaluate the space on the roadway) you must consider the working width of the barrier. The working width is connected with the barrier containment level.

What you don’t know is that not all the road barriers with high containment level (considering the H1, H2, H3 levels) have such a low working width.

Resulting with a W1 working width not only ensures the road barrier to safely operate but also saves meters on the road, gaining the necessary space for other road projects on the way where the barrier has been installed, especially when the barrier is applied in the median.

Furthermore, you need to consider the weight of the device during selection: a new jersey barrier weighs up to ten times more than a steel barrier.

And finally, the installation mode. In the assessment of the installation, it is important to carefully evaluate the morphology of the ground to decide whether to install a guardrail barrier or a bridge rail.

Now you may be wondering “what is a bridge rail?”

To well understand the difference, while the guardrail is fixed to the ground using driven posts, the bridge rail is fixed to the ground through resin plus anchoring pins on the concrete foundation. Not all manufacturers of road barriers can design them.

Innovation in road safety barriers

IMAGE 6 – EXAMPLE OF INSTALLATION ON VIADUCTS

Before delving into the technical characteristics of the Andromeda barrier, it is important to know that an aspect often underestimated is the aesthetic impact: this sometimes determines the choice of the designer depending on the environment in which the longitudinal barrier must be installed (like, for example, on roads that cross nature reserves, or viaducts).

IMAGE 7 – ANDROMEDA SMART LIGHT BARRIER
Andromeda has an innovative design that enhances the territory through its aesthetic characteristics. Andromeda is the only barrier on the Italian panorama that moves with the times, thanks to the integration with the smart system. Andromeda offers advantages in terms of lightness and ease of installation as it consists of pre-assembled modules. It is not a standard barrier, but it represents a new player on the road safety barrier field that links both guaranteed safety for passengers and the pleasure of driving on an elegant road connected with the environment: Andromeda is a smart light barrier that, thanks to integrated led, increases visibility in case of fog and rain, assuring a high level of road safety.

Andromeda – the intelligent barrier with high containment

Andromeda is not a traditional longitudinal barrier because it has a completely different structure compared to the classic barriers you see installed along the streets. The main feature of the barrier is the lightweight structure that entails several benefits.

The Andromeda barrier has been designed for every type of problem that the road manager or the designer must solve when it is necessary to come across a road rebuilding project or particular installation situation.
The versatility of the barrier also lies in this: two types of barriers in one solution.
Light and symmetrical, it is the ideal barrier for every need.

Andromeda, being composed of pre-assembled modules, also meets the needs of the installers because the installation takes place fast and quickly, streamlining the procedures and timing.

Also, the light and thin structure eliminates problems related to the footprint and weight: Andromeda weighs 1/10 of a concrete barrier. In some countries it has been indicated as a suitable solution for delimiting the lane of motorcyclists or the lane of pedestrians, then it also defines the lanes on bridges.

IMAGE 8 – BRIDGE INSTALLATION

It contributes to the enhancement of the territory thanks to its ability to adapt to the surrounding environment but especially in road sections where it is the only possible choice, allowing comfortable and safe driving.

Going into detail, the longitudinal barrier Andromeda is characterized by a containment level H2, with a transversal width of 120 mm and a working width of 600 mm (W1). It is a robust and safe barrier like no others offering high performance during deformation and saving space on the road at the same time.

It has a minimum installation length of 48 meters that guarantees performance even on narrow roads where the length of the road segment between the entrance and the exit is less than 80 meters, type to protect the service stations.

Andromeda is also available in the H4b model which has a footprint of 180mm and a working width of 800mm (W2) and a minimum installation length of 60 meters. This feature makes the barrier very different from those currently on the market, which are tested with a length of 80 meters.

IMAGE 9 – ANDROMEDA BRIDGE RAIL H4

This model also has features that allow its use as a double-sided median barrier, allowing a considerable recovery of space on the verge.

The Andromeda road safety barrier combines both active and passive safety because, unlike traditional road safety barriers, is distinguished by the equipment of an electronic system that greatly improves active safety on the road by providing better visibility, favoring the immediate intervention of emergency vehicles in the event of an accident.

The steel structure allows you to highlight the surrounding environment, reducing the visual impact that characterizes traditional barriers.

Briefly, a perfect combination of safety, technology, and aesthetics, chosen by those who want to protect motorists and enhance the territory.

Now you have all the information you need to choose the right barrier for you.

If you need more information, don’t hesitate to contact us to chat with our team to clarify your concerns.
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