What Are The Types of Road Safety Barriers?
Road safety barriers are designed to prevent vehicles from leaving a safe travel path, hitting unforgiving objects like trees, moving into hazardous situations like going down a cliff or rolling down a slope, and driving into oncoming traffic. These devices are also designed to reduce fatalities linked to accidents.
Although the installation of such barriers cannot guarantee complete safety or potential fatalities due to collision with the barricades, the devices have been proven effective in reducing the severity of impact on the vehicle and its occupants. That said, travel speeds, the angles at which the barricade are hit, the kinetic impact energy, vehicle ground clearance, and the number of vehicles involved, are all factors to take into consideration when considering the effectiveness of such a barricade.
If you are tasked with deciding which road safety barriers to install, read on as a brief overview of the types and features is provided below. The first distinction is whether the barricade is for permanent installation or temporary application.
Permanent types are made to be fixed in place. With this in mind, durability, cost of maintenance, applicability for the particular type of hazards against which it must protect, as well as the speed and ease at which repairs can be made must be taken into consideration. Examples are the W-beam guardrail, concrete barricades and wire-rope safety barriers.
Temporary devices are used to provide protection for a specific period against hazards associated with road works and risks like sinkholes or extensive road damage. Because of the temporary usage feature, these types of road safety barriers must be lightweight enough for easy and cost-effective transportation and deployment. In addition, the barricades must be able to withstand harsh weather elements and affordable enough to replace from time to time. Truck-mounted attenuators are an example.
Distinction Based on Rigid Features
Road safety barriers can also be categorised based on how rigid they are. For instance, a W-beam steel guardrail is semi-rigid whereas a concrete wall type is extremely rigid, and the wire-rope fence is the least rigid. Being the most rigid, the concrete wall blocks are the best at stopping a vehicle from breaking through but are also the least forgiving. Due to its rigid nature, concrete doesn’t give way at all, leaving the vehicle to take the full kinetic impact.
That said, these types of safety barriers are normally installed for side impact and have a sloped ridge at the bottom to deflect the vehicle back into its travel path when the wheels mount the ridge slope. These barricades are placed where it is essential to prevent breakthrough and where there is not enough space to install a W-beam guardrail that requires some clearance space behind it. The more rigid, the less likely that breakthrough will take place, so less clearance space is required. However, the more rigid nature also means less kinetic impact absorption capacity.
The W-beam guardrail is semi-rigid due to the panels being made from steel, attached to timber or steel posts. The steel can bend and give way, and the kinetic energy is absorbed across the entire system. This helps to give it more absorption capacity to take impact force away from the colliding vehicle and its occupants.
The wire-rope safety fence has a small horizontal footprint and is the least rigid, but it has superb kinetic impact energy absorption capacity. The impact is taken and disbursed along the wire-rope stretched between posts that give way upon high speed, high force impact.
Deflection capacity differs according to the barrier designs and materials. A concrete barrier’s sloped ridge helps to return the colliding vehicle to its original path. A W-beam guardrail, being semi-rigid also has some deflection capacity. It is one of the features that make these barricades suitable for installation next to roads as the vehicle is prevented from breakthrough upon side impact and is directed back into its safe travel path. The wire-rope fence has less deflection capacity but is sufficient to reduce impact damage to the vehicle.
Both the W-beam guardrail and the wire-rope fence have good impact absorption with the wire rope taking even more. Both disburse the energy throughout the system.
Repairs, Maintenance & Installation
The W-beam guardrail requires some clearance space for impact absorption and so does the wire rope fence. The concrete type requires no clearance space. The wire-rope fence has the smallest footprint and can be installed where surface space is limited, whereas the W-beam needs more space. All three types can be installed in the median of highways, although with the W-beam guardrail you need steel panels on both sides of the posts.
Both the W-beam and wire-rope systems are low on maintenance, made for durability, low cost to company, and quick repairs. These factors are important because regular maintenance or repairs that take a long time increase the risk for road users and workers.
Both types of barriers are highly visible in low-light conditions with reflective material, such as the V or D types of delineators to be installed on the W-beam steel panels.
Which Road Safety Barriers are the Best?
The type of safety barrier to install depends on factors like clearance available, the average speed of travel on the particular road, the types of vehicles and other road users like cyclists and motorcyclists, as well as protection for pedestrians, whether on an urban road or a rural or national road, whether in the median or the side, and the type of hazard against which to protect. In addition, the cost of maintenance, and cost of the particular barrier must be considered.
Where to Find More Information on the Road Safety Barriers?
Armco Superlite manufactures and supplies a wide range of road safety products, including temporary and permanent barriers. View the range of products for specifications, pictures and more information on each. Reach out to our consultants for help in deciding on the right barrier for your particular application requirements.